The Terrorism (Protection of Premises) Act 2025 (Martyn's Law) received Royal Assent on 3 April 2025. As we discussed in our earlier article, the Act places legal responsibility on the ‘responsible person’ (those in control of venues, events and public spaces) to have appropriate public protection procedures and measures in place to help keep people safe in the event of a terrorist attack.

There is no legal requirement to comply until the Act comes into force, which is not expected until spring 2027, but organisations may wish to consider what they need to do in advance.

A question that will arise for many organisations, and for the insurers who underwrite them, is: where premises are used for more than one purpose described in Schedule 1 of the Act, who is the responsible person? The answer depends on identifying the 'principal use' of those premises. The Terrorism (Protection of Premises) (Principal Use of Premises) Regulations 2026 and new guidance published by the government, address this. 

Determining the principal use is important not only to identify who the responsible person is, but also because it affects which compliance tier applies and therefore the full scope of obligations.

How is the principal use determined?

The guidance sets out a two-stage approach.

Stage 1: Purpose and nature of the premises

If individual premises have more than one Schedule 1 use, you should first determine which use relates most closely to the purpose and nature of the premises, taking into account the following factors:

• Whether the premises were built or have been modified to be used for a particular Schedule 1 use; 
• Whether the premises continue to be used for the same Schedule 1 use; 
• The physical characteristics of the premises (for example, the layout, size and specific features); and 
• Whether the premises are treated by a local authority (in the area in which the premises are situated) as having a particular Schedule 1 use - for example, by reference to planning permission, premises licences, alcohol licences, or entertainment licences. 

In many cases, this first stage will be sufficient to resolve the question. The guidance gives several illustrative examples where consideration of purpose and nature alone is determinative: a sports stadium built and still used for sport, with its pitch and spectator stands, will have its principal use identified as a sports ground; a hotel built and continuing to be used primarily to provide accommodation will have its principal use identified as a hotel; and a village hall built and still used as such will retain that as its principal use, even where it also hosts food and drink services and entertainment events.

Stage 2: All relevant circumstances

Where it is not possible to identify the principal use by considering the purpose and nature of the premises, the determination must be made on a case-by-case basis, taking account of all relevant circumstances.  At this stage, the following additional factors must be considered:

• Whether the whole of the premises, or only part of the premises, is occupied for each Schedule 1 use; 
• How much of the premises are occupied for each Schedule 1 use; 
• The amount of time that the premises are occupied for each Schedule 1 use during any period which is relevant in the circumstances of the premises; and 
• Whether one Schedule 1 use takes place to support another Schedule 1 use. 

This assessment could take into account information such as plans of the premises, licences, leases, operating hours, ticketing, staffing levels, capacity, floor area, and trading activity. "Amount of time" can refer to opening hours, days of operation, and seasonal activity, based on the individual circumstances of the premises. The principal use assessment should be reviewed if circumstances change, such as following refurbishment, a change to a licence, a change in how the premises is used or the activity that takes place there. 

What should organisations do?

For organisations operating mixed-use premises, the following practical steps are worth taking now:

1. Map your Schedule 1 uses: Review your premises against the Schedule 1 categories (see Annex A to the guidance for the full list) and identify whether more than one applies. This exercise should be carried out for each site individually.
2. Work through the two-stage test: Consider first whether the purpose and nature of the premises - including how they were built, how they are currently used, their physical characteristics, and how the local authority treats them - points clearly to a principal use. If not, gather the information needed for a full case-by-case assessment, including floor plans, licences, leases, operating hours, staffing levels and capacity data.
3. Identify the responsible person: Once the principal use is established, identify who holds control of the premises in connection with that use. Where premises are shared or partly operated by third parties under contractual arrangements, consider what co-ordination obligations arise and how those should be addressed in contracts, licences and operational arrangements.
4. Keep a written record: Once a determination has been made, it is advisable to keep a record of the determination and the reasoning for it. This will be important both for regulatory purposes and for evidencing a systematic and considered approach should questions arise later.
5. Review when circumstances change: The principal use assessment should be reviewed if circumstances change, such as following refurbishment, a change to a licence, a change in how the premises is used or the activity that takes place there. 

We have specialist lawyers at Browne Jacobson who can assist your organisation in working through the principal use determination for your premises, identifying the responsible person, and preparing for the Act coming into force. We also advise insurers on the implications of Martyn's Law for underwriting strategy, policy wordings, and claims handling.

This article is for general information purposes only and does not constitute legal advice. If you require advice specific to your circumstances, please contact us.