Martyn's Law, and the premises it will touch

Most building-safety regulation arrives aimed at a recognisable type of property: high-rise residential, rented homes, public-sector estates. Martyn's Law is different in reach. The Terrorism (Protection of Premises) Act 2025 attaches duties to premises and events by their capacity, which means it touches venues that have never thought of themselves as part of the safety-and-compliance world at all. A village hall, a mid-sized conference room, a place of worship and a shopping centre can all fall within scope, and the question that decides it is simply how many people the place can hold.

That breadth is the headline. The detail is more measured, and the timeline gives operators room to prepare rather than scramble.

What the Act does, and when it bites

The Terrorism (Protection of Premises) Act 2025 received Royal Assent on 3 April 2025, according to guidance from the Home Office and ProtectUK and analysis by Mayer Brown. It does not take effect immediately. The same sources describe an implementation period of at least 24 months, so the duties are expected to apply from around 2027. The regulator will be the Security Industry Authority (SIA).

The aim is to make publicly accessible premises consider the risk of a terrorist attack and take proportionate steps to reduce harm. It is, deliberately, not a counter-terrorism specialism dropped onto venue managers. The standard expectation is closer to good preparedness: knowing your premises, knowing how people would get out, and having thought about what staff would do.

The two tiers

The Act splits in-scope premises into two tiers by capacity, as set out by ProtectUK.

The standard tier is meant to be achievable without specialist cost. The enhanced tier, covering larger premises and events, carries a heavier expectation around assessment and documentation. Knowing which tier a site sits in is the first practical decision, because it sets the size of everything that follows. Capacity, not floor area or sector, is the line.

What "proportionate" tends to mean in practice

Because the duties are framed around proportionate harm reduction rather than a fixed checklist, the temptation is to wait for perfect clarity before doing anything. That tends to be a mistake. The measures most likely to matter are the ones that any well-run venue could describe today:

• Knowing the real capacity of each space, and not just the licensed headline figure.
• Understanding the routes people would use to leave, and keeping them usable rather than blocked with stock or furniture.
• Briefing front-of-house and event staff so the response is a trained habit, not an improvisation.
• Keeping a record of what was assessed and decided, so the reasoning survives a change of manager.

None of that requires waiting for the regulator. It requires knowing your premises well enough to answer questions about them under pressure.

The records problem, again

Martyn's Law shares a feature with almost every other strand of building regulation: the duty is only as strong as the operator's ability to show what was done. For enhanced-tier premises in particular, an assessment that lives in one person's head is worth very little when that person leaves. The same goes for a procedure that was briefed once and never written down.

The premises that will find compliance easiest are those that already hold their site information in one place: the layout, the exit routes, the capacity figures, the staff who have been briefed and when. Many of these venues are mixed-use, sitting at the base of a residential block or inside a managed estate, where the building above already carries its own safety obligations. Pulling the security-preparedness record into the same system as the rest of the building's compliance avoids running two parallel filing systems that drift apart.

Where it overlaps with the building

A venue's evacuation thinking does not stop at the security threshold. The routes people would use to leave during an attack are largely the same routes they would use in a fire, and the plans that describe them are the same plans. That overlap is an opportunity. A premises that has already drawn clear, current building plans and thought hard about how people move through the space has done much of the spatial work Martyn's Law will ask for.

It also connects to broader evacuation planning. Our note on evacuation planning, and the people who need it most covers the human side of getting people out, which Martyn's Law brings into sharper focus for public venues. Holding all of it against a single compliance calendar keeps the security review from becoming the obligation everyone forgets between busy seasons.

A short, practical close

The implementation period means there is time, but time has a way of evaporating. The sensible move now is not to draft a counter-terrorism policy; it is to find out which tier each premises falls into, confirm the real capacity, and make sure the layout, exit routes and staff briefings are written down somewhere durable. SAMRISK keeps that kind of site information in one place, which means when the duties land in around 2027 the answer to most questions is already on file rather than waiting to be assembled. This is general information, not legal advice, and the detail of the regime may develop before it takes effect.