What Martyn's Law obligations do corporate headquarters have?

Most flagship corporate headquarters land in Martyn's Law enhanced tier (800+ capacity) once combined office headcount, visitor density and event-space capacity are counted on a single qualifying day. Standard tier (200 to 799) applies to smaller HQs, regional head offices and single-floor occupancies. The capacity calculation is what the responsible person can reasonably expect on the busiest day across all qualifying spaces, not a daily average.

The town hall and all-hands space is usually the trigger. A 1,000-capacity town hall room used three or four times a year for staff-wide events pulls the whole site into enhanced tier even if the day-to-day office population is lower. Internal product launches, partner conferences, charity fundraisers and customer events held in HQ event suites all count toward the qualifying capacity. Treat the town hall room's published capacity as the reference number when scoping obligations, then validate with a competent advisor.

Coordination duty matters disproportionately for HQs in landlord-managed buildings. Most City of London, Canary Wharf, Manchester Spinningfields, Edinburgh St Andrew Square and Leeds South Bank office towers operate as multi-tenant assets with the landlord acting as the responsible person for shared spaces (lobby, lifts, plant, public realm). The HQ tenant remains responsible for everything inside the demise. The legal duty is to coordinate with the landlord on shared-area procedures, signage, evacuation routes and lockdown triggers, not to design those areas in isolation. Establish the coordination interface at fit-out brief stage with the Martyn's Law assessment so it is in the building manual, not a side conversation.

Implementation considerations for the AV and life-safety layer:

• Digital signage emergency override. The CMS must accept a priority signal from the fire panel or mass notification system and replace all content with evacuation, invacuation or lockdown messaging instantly across every screen.
• Voice alarm and public address. Voice is the first route for evacuation messaging in any space above 100 capacity; the system must reach every occupied zone with intelligibility tested per BS 5839-8.
• Mass notification. SMS plus push notification to staff devices via the corporate identity platform (Azure AD, Okta) for incidents that escalate beyond the building.
• Lockdown trigger panels. Discreet panels at reception, concierge and security control with a single positive action that initiates lockdown across signage, voice alarm, access control and mass notification simultaneously.
• Access-control integration. Door release behaviour for invacuation (lock down public-facing routes, hold staff routes open) configured into the access-control schedule, not improvised on the day.

The practical lesson from early enhanced-tier compliance work: programme this into the Cat B fit-out, not as a retrofit. Cabling, ceiling routes, panel positions and integration points are far cheaper to specify alongside the rest of the HQ AV programme than to retrofit once joinery, ceilings and access control are commissioned.

Quick reference: flagship HQ usually enhanced tier (800+ via combined office + event capacity), smaller HQ standard tier (200-799), town hall capacity often the trigger, coordination duty with landlord in multi-tenant towers, integrate signage override + voice alarm + mass notification + lockdown panels into Cat B fit-out from the start.