Large-Group Immersive Event London: Conferences, All-Hands, 100 to 300 People

Annual conferences, all-hands events, away days for major populations, partner conferences and major workforce-communication moments are some of the most consequential L&D opportunities in the corporate calendar. The audience is gathered, attention is concentrated, and the institutional investment in the event is substantial. Yet most large-group corporate events default to keynote-and-panel programming that produces awareness without sustained behaviour change. Sidestream's large-group immersive event format is the alternative for organisations that want their major workforce events to produce observable cultural and behavioural outcomes rather than satisfaction-survey scores. This page is the working reference for HR Directors, Heads of Communications, Heads of Events and senior leaders scoping major workforce events.

The guide runs to roughly 4,400 words.

Which page is for what: this page covers only the large-group format, audiences of 100 to 300 in a single performance, and the venues, occasions and follow-through that go with that scale. How an immersive event is scoped, how a production runs and what shapes the cost are on our immersive events London page; the productions themselves are introduced on the immersive events overview.

What a Sidestream Large-Group Immersive Event Is

A Sidestream large-group immersive event combines three integrated components into a coherent behaviour-change intervention for audiences typically between 100 and 300 people.

The immersive theatre production. Sidestream's three established productions (The Death of Jane Doe, The Accused, Top of the Cops) are full immersive-theatre works performed by professional actors. The production runs typically 45 to 75 minutes depending on the format. The audience experiences a structured narrative that operationalises the behavioural target through lived narrative rather than content delivery.

Structured post-performance work. The performance is followed by structured small-group discussion, plenary debrief, and structured commitment-making that translates the lived experience into specific behavioural intention. The post-performance design is calibrated to the audience composition, the institutional context and the specific behavioural target the event aims to move.

Embedding architecture. The third component is the embedding architecture that runs after the event itself. This typically includes cohort-level follow-through workshops, leadership accountability sessions, behavioural-observation reviews, and adjustment to the workplace conditions that affect the target behaviour. The embedding turns the event from a memorable experience into an observable behaviour-change intervention.

The combination of components is what distinguishes Sidestream's format from theatre-only productions (which lack the embedding architecture) and from conventional corporate events (which lack the lived-experience production). The output is observable behavioural and cultural change at the scale that major workforce events can address.

The Three Established Sidestream Productions

The Death of Jane Doe

The Death of Jane Doe addresses mental health stigma in frontline work and was recognised at the CorpComms Awards; the production, the judges' comment and the audience response are described on the immersive events London page. At large-group scale it suits workforces where that stigma has to be tackled across a whole population at once: NHS clinical workforces, police forces, university populations and corporate workforces under significant change or operational pressure.

The Accused

The Accused addresses equality, diversity and inclusion through lived experience and was commended at the Goldsmiths Public Engagement Awards 2018. For a hall of 100 to 300 it suits workforces where EDI has to move beyond policy compliance into observable behaviour: harassment-prevention work under the October 2024 Worker Protection Act duty, the NHS Sexual Safety Charter, university EDI charter marks, and corporate EDI programmes where awareness-only delivery has not produced change.

Top of the Cops

Top of the Cops is the leadership and reputation-management production set at an 80s punk gig. In the large-group format it is the production for senior leadership populations, particularly where conventional leadership development has produced satisfaction-only outcomes and the audience needs an unconventional method before it will engage seriously.

London Venues for Large-Group Immersive Events

Sidestream advises on venue selection as part of the event design. The venue choice depends on audience size, production format, the institutional context and the specific cultural register of the brief. Common London venue options:

The Roundhouse (Chalk Farm Road, NW1). Iconic former engine shed converted into a performance and creative venue. Suitable for the largest-format productions, with audiences at the top of the 100 to 300 range. The venue's cultural heritage adds significant cultural resonance to the production-format work.

KOKO (Camden High Street, NW1). Former music hall reopened in 2022 after major restoration. Particularly well-suited to music-industry-context productions and creative-sector audiences. Its capacity of roughly 1,400 is well above the maximum of around 300 for a single performance.

Trinity Buoy Wharf (East India Docks, E14). Iconic Canary Wharf-area immersive-friendly venue with distinctive character. Particularly suitable for tech-cluster and financial-services audiences.

Cecil Sharp House (Regent's Park Road, NW1). The English Folk Dance and Song Society's HQ, with a main hall suitable for medium-cohort productions in the 100-200 range.

Camden People's Theatre (Hampstead Road, NW1). Smaller theatre venue suitable for intimate productions in the 50-100 range.

The Forge (Delancey Street, NW1). Camden Town venue suitable for productions in the 60-120 range.

UCL central campus (Gower Street, WC1). UCL's main estate has several lecture theatres and performance spaces suitable for academic-client production-format work.

Kings Cross venues (Pancras Square area, N1C). The Kings Cross development includes multiple immersive-friendly venues suitable for tech-cluster and creative-industry productions.

Client venues. For organisations with in-house auditoriums, conference centres or events spaces suitable for the production format, client-venue delivery is available. This includes major corporate auditoriums in the City and Canary Wharf, NHS trust education centres with appropriate facilities, Civil Service conference venues, and adjacent contexts.

Hotel venues. For multi-day conferences and away days where social and reflection programming sits alongside the production, hotel venues across central London accommodate the brief. Sidestream advises on suitable venue partners.

Leadership Conferences, All-Hands and Other Corporate Event Contexts Where the Format Suits

Sidestream's large-group format suits seven distinct corporate event contexts.

Annual conferences. Annual workforce or partner conferences for populations from 100 to 300. The production-format anchor provides the cultural-and-behavioural focal point for the wider conference programme. Pre and post-performance work integrates with the conference's broader content programme.

All-hands workforce events. Major workforce-communication events where the entire workforce (or major business unit) is gathered. The production format provides the kind of memorable cultural moment that all-hands events aspire to deliver but often fail to achieve through conventional keynote-and-panel programming.

Away days for major populations. Senior leadership team away days, major divisional populations away days, professional-services partner conferences. The production format provides the structured cultural anchor that the away day's social and reflection programming sits around.

Partner conferences in professional services contexts. Magic Circle law firm partner conferences, Big-4 partner conferences, professional services partner-level gatherings. The production format reaches senior populations that conventional partner-development programming often fails to engage.

Supplier and customer events. Major supplier or customer events where the organisation wants to deliver memorable cultural communication alongside the commercial purpose of the event.

Major workforce-communication moments. Strategic-shift communication, post-merger integration events, leadership-transition events, post-incident workforce-engagement events. The production format provides cultural framing that conventional communication cannot match.

Leadership conferences for senior populations. Senior leadership conferences across organisations or sectors. Top of the Cops, the leadership production, is the natural starting point for these audiences.

Sector Application Notes for Large-Group Immersive Events

Public Sector Large-Group Events

UK Civil Service, NHS, police-sector and local-authority large-group events benefit particularly from the production format because the public-sector context often involves audience populations sceptical of corporate-style content delivery. The award-recognised productions provide intellectual and creative credibility that conventional alternatives lack. See our Westminster and Whitehall guide, Police Leadership Training guide and NHS guide.

Higher Education Large-Group Events

UK university large-group events (faculty conferences, university-wide cultural events, postgraduate conferences, alumni events) benefit from the production format because the audience sophistication and academic culture welcome the creative-and-intellectual depth of the productions. The Goldsmiths Public Engagement Awards 2018 commendation of The Accused reflects the natural fit. See our University Leadership Development guide.

Financial Services Large-Group Events

City of London and Canary Wharf financial services large-group events (annual partner conferences, regulator-engagement events, workforce all-hands during transformation periods) benefit from the production format because financial services audiences are typically sceptical of conventional corporate development content. The production format reaches these audiences through different means. See our City of London guide and Canary Wharf guide.

Professional Services Large-Group Events

Magic Circle law, Big-4 accounting and adjacent professional services partner conferences benefit particularly from the format because the partner audience is structurally difficult to reach through conventional programming. Top of the Cops, built around crisis leadership, is the production to consider for senior populations of this profile.

Technology Sector Large-Group Events

Kings Cross, Shoreditch and London tech-cluster large-group events (company all-hands, sector conferences, investor events) benefit from the production format because the tech audience values creative and unconventional programming as cultural signal. Trinity Buoy Wharf and Kings Cross venues are particular fits for this audience.

Creative Industries Large-Group Events

Camden, Soho and creative-industry large-group events benefit naturally from the format because the audience is itself creative-industry and recognises the production craft. Camden venues including the Roundhouse and KOKO are particular fits.

Cross-Sector Conference Events

Cross-sector events (industry-body conferences, professional-body annual meetings, government-and-industry partnership events) benefit from the production format because the diverse audience composition requires programming that reaches across sector cultures. Top of the Cops has been performed for cohorts of leaders from different sectors, and the productions can be adapted for mixed audiences.

Cost and Procurement for London Large-Group Immersive Events

• Formats scale from a single performance for an audience of up to 200, through a larger performance for 200 to 300 with structured pre and post-performance work, to multi-performance series, combined production-and-workshop programmes and bespoke original productions. All are priced per engagement.
• What shapes the cost of each format is set out under costs by event scale on our immersive events London page; this page adds what changes at large-group scale.

Which procurement route applies, direct contracting or a sector framework, is something we clarify in the first conversation.

How Sidestream's Format Produces Behaviour Change at Scale

The structural challenge of large-group corporate events is producing behaviour change at scale. Conventional formats (keynote speakers, panel discussions, expert presentations) produce awareness reliably but rarely produce observable behaviour change at the workforce level. The cumulative effect of one keynote-led event after another leaves the audience inspired but unchanged in operational practice.

Sidestream's format addresses the scale-change problem through three mechanisms: lived experience in place of content delivery, structured post-performance work that turns experience into intention, and an embedding architecture that turns intention into practice. All three are described in full on the immersive events London page. At large-group scale the second and third carry the weight: three hundred people have watched the same scene, and the follow-through has to convert that shared reference into practice across teams that go back to working separately.

Planning Timeline for a Large-Group Event

The six-stage sequence is the same one we run for every immersive event, from discovery and design through to Kirkpatrick Level 3 measurement. It is set out in full on our page for immersive events in London. What changes at 100 to 300 people is the front half.

• Venue scoping starts earlier. A room that seats 300 with clear sightlines to a performance area is a different search from a workshop space for 25, and in central London it is booked further ahead.
• Technical specification carries more weight. Sound reinforcement, lighting and staging have to work for the back row, or the people furthest from the action disengage and the behavioural effect is lost on the part of the audience you most wanted to reach.
• Audience preparation becomes its own workstream. With a workshop cohort the context can be set in the room. With an all-hands audience it has to be set before people arrive, and it has to reach every division rather than one team.
• Post-performance work needs facilitation capacity. Structured conversation after the production is where behaviour change actually starts. At this scale that means briefed table facilitators, not a single voice from the stage.

Plan on twelve weeks from first conversation to event day. Where time is tighter, the practical minimum is eight to ten weeks, using an established production with light customisation. With longer windows, deeper customisation is possible, including substantial script adaptation, bespoke scenario integration and full sector-specific calibration.

What Changes When the Audience Is 300 People

The market conditions behind immersive event demand are the same whatever the audience size, and we set out the five shifts that have shaped them since 2024 on our page for immersive events in London. Three things behave differently once the room holds hundreds rather than dozens.

The measurement problem gets harder, and more valuable. With a workshop cohort you can observe every participant. With 300 people you cannot, so behavioural measurement has to be designed as sampling from the start: named populations, agreed observers, a baseline taken before the event rather than reconstructed after it. Buyers who skip that step end up back at satisfaction scores, which is precisely what a large-group budget cannot be defended with.

The audience is not one audience. An all-hands or conference room holds people with very different stakes in the behaviour you are targeting: the population whose conduct is in question, the population affected by it, and the leaders who set what is tolerated. A production that lands with one of those groups can alienate another. Casting the scenario against that mix is the work that distinguishes a large-group production from a scaled-up workshop.

Follow-through decides whether anything survives the day. A single shared experience creates a common reference that a series of separate workshops never can, and that is the format's real advantage. It is also perishable. Without cohort-level follow-on work in the weeks afterwards, a large-group event is remembered as an event rather than acted on as a change of expectation.

How to Start a Large-Group Immersive Event Engagement with Sidestream

Book a free 30-minute consultation at calendly.com/info-sidestream. Bring the occasion, the size and mix of the audience, the date, any venue constraints and the behaviour you want the event to move. We will say which of the three productions fits, whether the audience is really a large-group brief or a cohort one, and where bespoke production work would be needed.

Or read more on our immersive events page covering the productions in detail, our immersive simulation training London page, our comparison of immersive training and e-learning, our employee workshops topic guide, our services, our approach, our case studies including Metropolitan Police, UCL and Goldsmiths work, our London locations, and our 50-provider UK comparison.

Frequently Asked Questions

Questions that apply to every immersive event (customisation, bespoke productions, sensitive content, delivery outside London, measurement, filming, hybrid audiences, lead times, internal communications and integration with other speakers) are answered on the immersive events London page. The questions below are specific to the large-group format.

Can Sidestream's large-group format accommodate audiences larger than 300?

For audiences larger than 300, we typically schedule multiple performances across the workforce rather than a single very-large-audience performance. The maximum single-performance audience that maintains the intimacy and behavioural-impact of the immersive method is approximately 300. Beyond that scale, the lived-experience quality degrades and the post-performance work becomes harder to structure productively.

What is the difference between Sidestream productions and conventional theatre productions?

Conventional theatre productions are designed for audience entertainment and aesthetic experience. Sidestream's productions are designed for behavioural and cultural intervention, with the theatrical craft applied to specific organisational-behaviour targets. The same theatrical skills are at work; the design intention is different. The productions are also delivered with structured pre and post-performance work that conventional theatre does not include.

Can Sidestream work with the client's events team or AV providers?

Yes. The production has specific technical requirements that we communicate clearly in advance, and we work positively with the client's wider event-delivery infrastructure.

What is the maximum number of performances Sidestream can deliver in a single engagement?

In a multi-performance series, the number of performances follows the size of the workforce, the number of sites and the time window available. Specific capacity is set at the engagement design phase.

Can Sidestream's productions support media or external-audience engagement?

Sidestream's primary positioning is internal-workforce behaviour change rather than external communication. For specific external-engagement events (industry conferences, sector-association events, public-sector engagement events) the productions can be performed for mixed internal-external audiences where the engagement brief supports it.

How do Sidestream's productions compare to other corporate-theatre providers?

Several UK corporate-theatre and immersive-event providers operate in the wider market, alongside practitioners working in the forum-theatre tradition. Sidestream's specific differentiation is the combination of award-recognised production craft, co-founder Ben Laumann's research roots at UCL, Cambridge and Bocconi, the Kirkpatrick Level 3 measurement architecture, and the verified client base including Metropolitan Police, UCL, Cambridge, Bocconi, Goldsmiths and Imperial. For comprehensive comparison, see our 50-provider UK comparison guide.

Can the large-group format be integrated with broader behaviour-change consultancy?

Yes. A large-group event can be combined with wider behaviour-change consultancy work, including workshop programmes for the audience populations after the event, leadership development for the senior population, and organisational-development consultancy on the workforce conditions that affect the target behaviour.

What is the typical event-day timeline for a Sidestream large-group immersive event?

A standard event-day runs approximately three to four hours from arrival to close. Audience arrival and pre-event welcome (30 minutes), pre-performance framing and context-setting (15 minutes), production performance (45 to 75 minutes depending on the production format), structured small-group post-performance discussion (45 minutes), plenary debrief and commitment-making (30 minutes), close and onward signposting (15 minutes). For events with extended programme integration, the production element sits within a wider half-day or full-day event structure.

How does Sidestream handle high-profile or sensitive event contexts?

The productions can be adapted for high-profile audiences (senior leadership of major institutions, political figures, regulator audiences, press-attended events). The production design and the wider engagement protocol accommodate the specific protocol and confidentiality requirements of these contexts. Pre-event protocol design is conducted in close collaboration with the client's events and communications teams.

Can Sidestream's productions support multi-language or international audience composition?

The productions are typically performed in English (British). For international audiences with substantial non-native-English populations, we provide structured context-setting and post-performance interpretation support where appropriate. For specific multi-language requirements, calibration is set at the engagement design phase.

Does Sidestream offer post-event resources for audience members?

Yes. Post-event resources can include cohort-level workshop opportunities for audience populations, follow-up content materials, leadership-team toolkits for the audience populations' line managers, and integration materials that link the production experience to ongoing organisational-development work. The specific post-event resource package is set at the engagement design phase.

What feedback have Sidestream's productions received?

The feedback we can quote relates to the productions rather than to any particular large-group event. Helen Dunne of the CorpComms Awards Panel said of The Death of Jane Doe: "The judges loved the creative approach to building awareness, well executed and an excellent mix of theatre and immersive work." A programme participant commented: "When else can you have an honest talk with someone living with a serious mental health condition, except through immersive theatre?"

How does Sidestream's large-group format scale across multi-site organisations?

For multi-site organisations with substantial workforces, the production-format work can be delivered across sites through scheduled performance series. The combination of multi-site delivery with consistent production architecture produces organisation-wide cultural change that single-site events cannot deliver.