Arenas and concert venues were the primary motivation for Martyn's Law. Every arena in the UK is Enhanced Tier.
The Terrorism (Protection of Premises) Act 2025 received Royal Assent in April 2025. It was named after Martyn Hett, killed at the Manchester Arena in 2017. Arenas and major concert venues face the most significant compliance obligations under the Act.
Two months free. No hardware. No commitment beyond the conversation.
01 / Which Tier
There is no Standard Tier question for arenas. Every arena in the UK is Enhanced Tier.
The Enhanced Tier threshold is 800 qualifying capacity. The smallest purpose-built UK arena, the Utilita Arena in Aberdeen, holds over 15,000. The O2 in London holds 20,000. The Co-op Live in Manchester holds 23,500. Every arena, indoor concert venue and major outdoor amphitheatre in the UK exceeds the Enhanced Tier threshold by a factor of many times.
The Martyn's Law obligation for arena operators is therefore not a question of which tier applies. It is a question of what the Enhanced Tier specifically requires and how to satisfy it before April 2027 when enforcement begins.
Enhanced Tier venues must appoint a designated responsible person, conduct and document a vulnerability assessment, implement active physical protective measures and be able to demonstrate proportionate safety controls when the Security Industry Authority conducts its assessment. The documentation of active monitoring is central to what the SIA will assess.
- Designated responsible person appointed
- Documented vulnerability assessment completed
- Active physical protective measures in place
- Documented evidence of active monitoring for SIA
- Registration with the Security Industry Authority
- Staff training appropriate to Enhanced Tier obligations
The Manchester Arena attack is the origin of this legislation.
Martyn Hett was killed in the Manchester Arena foyer on 22 May 2017. The Act is named after him. Arena operators carry both the legal obligation and the moral weight of that history. Compliance is not optional and the 2027 enforcement date is firm.
02 / What Measures
Arenas already have CCTV. The question is whether it is active enough to satisfy the Act.
Every major arena in the UK has an extensive IP camera network. Control rooms staffed by security personnel monitor those cameras during events. On the face of it, this looks like active monitoring. But the Act draws a specific distinction that matters here: passive recording is not the same as active detection.
A human operator watching a wall of screens during a 20,000-person event cannot realistically detect all of the behavioural anomalies that might indicate a developing threat. Attention degrades. Coverage gaps exist. And critically, there is no documented detection log that the SIA can review to confirm that active monitoring was in place.
AI behaviour detection addresses all three of those problems. It monitors continuously across every camera in the network without attention fatigue. It detects anomalies the moment they appear and alerts the control room team with a clip and a location. And it creates an automatic, timestamped detection log that documents active monitoring for every event, every hour.
For arena operators, that detection log is what satisfies 'proportionate' under the Enhanced Tier standard. It is the difference between saying you monitor and being able to prove it.
The foyer is the highest-risk zone in any arena.
The Manchester Arena attack happened in the City Room foyer during the post-show exit. That is the window when the largest number of people are concentrated in an unstructured space outside the controlled seating bowl. Detection in foyer areas is not optional for arena operators.
Detection needs to cover the full event lifecycle.
Pre-show arrival, interval, post-show exit and the overnight period between events each carry different threat profiles. Continuous AI detection covers all of those windows, not just the period when the arena is full.
Runs on existing camera infrastructure. No hardware replacement required.
Archangel deploys as a detection layer on top of your existing IP camera network. The compliance route for arenas is not a capital project. It is adding intelligence to the infrastructure already in place.
03 / How AI Behaviour Detection Helps
What Archangel detects in an arena or concert venue environment.
Foyer and concourse loitering
Extended loitering in arena foyers, concourse areas and public thoroughfares is the clearest pre-attack behavioural indicator in large-venue environments. Detection creates the intervention window that passive recording cannot.
Crowd surge and anomaly detection
Unusual crowd movement in concourse areas, corridor pinch points or near entry gates is detected in real time. Early warning allows the control room to respond before a situation escalates.
Unattended items in public areas
Bags or items left unattended in foyers, concourses, toilets or seating approach corridors are flagged immediately, giving security the time to respond before the surrounding area is affected.
Perimeter and external area monitoring
The area immediately outside an arena, including queuing zones, drop-off points and approach routes, are covered as well as internal spaces. External reconnaissance behaviour is flagged before an individual enters.
Tailgating through backstage and production access
Arena backstage areas, production corridors and artist access routes have controlled entry. Detection flags individuals following authorised personnel through restricted access points.
Documented detection log for every event
Every alert, confirmed detection and control room response is logged automatically for each event. That log is the documented evidence of active monitoring that the SIA will review under Enhanced Tier compliance.
For the full guide to Martyn's Law, including the implementation timeline and what proportionate physical measures mean in practice, visit our main guide.
Read the full Martyn's Law guideStart the compliance conversation for your arena now.
Book a discovery call. We will assess your existing camera infrastructure, your event schedule and what active AI monitoring looks like across your specific venue. Two months free means you can start before enforcement begins without committing to long-term costs up front.
Two months free. No hardware. No commitment beyond the conversation.