“Our school never has 200 visitors” is usually accurate, and it is answering the wrong question. The threshold under the Terrorism (Protection of Premises) Act 2025 is 200 or more individuals reasonably expected on site from time to time — everyone who is there, not everyone who signs in.

Pupils, teaching staff, support staff, volunteers and visitors all sit inside the same total. Once they are added together, the vast majority of schools will find themselves in scope.

The count is not a category of person. It is a headcount of the site. Everyone reasonably expected to be there goes into it:

• Pupils. The largest single group at almost every school, and the one most often left out of the estimate entirely.
• Teaching staff. Everyone timetabled, plus cover and peripatetic staff who are on site regularly.
• Support staff. Groundskeepers, the site team, handymen, kitchen staff, office and administrative teams. Any and all of them are part of that 200.
• Volunteers. Parent helpers, reading volunteers, governors on site, anyone giving their time rather than being paid for it.
• Visitors. Parents, contractors, visiting teams, external speakers, peripatetic services.

It would be easy to read the above as “count your staff as well as your visitors”. That still understates it.

The 200 is everyone on site at once, combined. Not the busiest group, not staff plus visitors, not the number in the visitor book with a margin added. If 200 or more individuals are reasonably expected on the site from time to time, the threshold is met.

This is also why the objection feels so reasonable when a school raises it. A school genuinely may never see 200 external visitors in a year. That has no bearing on whether 200 people are expected on the site.

The threshold does not describe an average day. It describes any occasion you can reasonably foresee.

For schools that points straight at the calendar. Nativity plays and the Christmas concert are the clearest example — a hall full of parents, on top of the pupils and staff who are on site anyway. Parents evenings, sports days, open evenings and school productions do the same thing.

If you can foresee it happening and it is going to breach the 200-person threshold, that puts you in scope. It does not matter that it happens on a handful of days a year.

Take a school with 100 pupils. Add the teaching staff who run it. Add the office, kitchen and site teams. That is a base figure well above 100 before any visitor arrives.

Now add nativity night, where a substantial share of those pupils brings one or two adults with them. A school of 100 pupils will almost certainly tend to breach the 200-person threshold, and larger schools clear it without needing an event at all.

One distinction is worth holding onto. The threshold is about the number of people reasonably expected on site, not the number the buildings could physically hold. Fire capacity figures are not the test and will usually give you the wrong answer in both directions.

You are also not expected to have counted precisely. The duty is to make a reasonable estimate of what you expect, using what you already know — roll numbers, staff lists, ticketed attendance at events. Our Am I in Scope? tool asks for the attendance you expect and returns your scope position from it.

Being in scope means having four public protection procedures in place so far as is reasonably practicable — evacuation, invacuation, lockdown and communication, as four distinct items. Nothing is submitted to the regulator for approval at standard tier, and the school must be able to evidence those procedures on inspection.

Prova Risk builds all four around your site, holds the training and exercise records against them, and produces a single compliance document you can put in front of a regulator. £399 per year per site.

• Does Martyn’s Law apply to schools?
• Counting peak attendance rather than a normal day
• Counting attendance without a clicker on the door
• Capacity is not the same as expected attendance
• The 200-person threshold under Martyn’s Law
• How do I know if my premises reaches the 200-person threshold?
• Martyn’s Law hub