INTRODUCTION

  • The Terrorism (Protection of Premises) Act 2025 (the Act), commonly known as Martyn’s Law, received Royal Assent on 3 April 2025. Named in memory of Martyn Hett, one of the 22 victims of the 2017 Manchester Arena attack, the legislation represents a significant shift in how venues open to the public must approach security and counter-terrorism preparedness. For owners and operators of Historic Houses—particularly those that open to the public or host events—understanding and preparing for these new obligations is essential.
  • The Act aims to improve public safety by requiring venues to take proactive steps to mitigate terrorism risks. Implementation is expected approximately 24 months after Royal Assent, meaning the requirements are likely to come into force around April 2027. This provides a window of opportunity for those responsible for historic properties to assess their obligations, review existing practices, and prepare for compliance.

SCOPE OF THE LEGISLATION

Martyn’s Law applies to both premises and events (both indoor and outdoor) where public attendance reaches certain thresholds. Historic Houses that welcome visitors or host functions may fall within the scope of the Act depending on their expected attendance figures.

PREMISES

A premises will fall within the scope of the Act where it satisfies all of the following four criteria.

  • There must be at least one building on the premises.
  • The premises must be wholly or mainly used for one or more of the uses specified in Schedule 1 of the Act.

The most relevant uses specified in Schedule 1 for Historic Houses are likely to be as follows:

  • A venue for hire for events or activities
  • A visitor attraction of cultural, historic, touristic or educational value
  • Sale of Food and Drink
  • Retail
  • It must be reasonable to expect that at least 200 individuals may be present at least occasionally.
  • The premises must not be excluded under Schedule 2 of the Act. The most relevant exclusion for Historic Houses is a park or recreation ground where not measures are taken to check if a visitor has paid for entry, is a ticket holder or a member. This would be relevant, for example, to the Hyde Park in London.

EVENTS

Events will fall within the scope of the Act where they satisfy the following criteria:

  • The event will take place at premises within Section 3(1)(a) of the Act. A qualifying event can take place on land whether or not it includes a building (this is in contrast to the definition of qualifying premises under the Act which needs to include a building). The Premises at which the event is to be held must not be enhanced duty premises as the enhanced duty premises are already subject to the enhanced tier obligations under the Act.
  • The relevant premises are accessible to members of the public for the purposes of the event.
  • It must be reasonable to expect that there will be at least 800 individuals present at the event at some point during it.
  • There are measures to check entry, such as ticket checks.
  • The event is not be excluded under Schedule 2 of the Act.

THE TWO-TIER SYSTEM

The obligations under the Act are set out in a two-tier framework, with obligations increasing according to expected attendance. The aim of the obligations is to ensure that appropriate public protection procedures are in place to reduce the risk of physical harm being caused to individuals if an act of terrorism was to occur at the Premises or the Event.

Standard Tier

The Standard Tier obligations apply to Premises only (and not to Events). The Standard Tier obligations apply where it is reasonable to expect that 200 to 799 individuals may be present at the Premises least occasionally.

Those responsible for Standard Tier premises must notify the Security Industry Authority (SIA) of their status, ensure that relevant staff and volunteers receive terrorism awareness training, develop and maintain a basic preparedness plan, and establish clear procedures for staff and volunteers in the event of an incident. These procedures should include evacuations (moving to a place on the Premises where there is less risk) and procedures for preventing individuals entering or leaving the Premises. There should also be clear procedures for disseminating information. There is no requirement under the Standard Tier to implement physical security measures.

Enhanced Tier

The Enhanced Tier obligations apply to both Premises and Events where it is reasonable to expect that 800 or more individuals may be present at least occasionally. The Enhanced Tier obligations include all of the Standard Tier requirements, plus the preparation of detailed risk assessments to be provided to the SIA, the development of a comprehensive security plan, and the implementation of additional security measures relating to monitoring of the premises and the vicinity.

You will need to consider how you will assess the number of individuals who may be present at least occasionally at the Premises or the Event. You can, for example, use advanced ticket sales or it may be useful to collect attendance data from existing events/openings so that you can form a reasonable view as to how many individuals “may be present”. Some of this information will be overlapping with the data that you are collating for other regulatory compliance, for example, licensing and Fire Risk Assessments.

THE RESPONSIBLE PERSON

  • Identifying who bears responsibility for compliance is critical, particularly for Historic Houses where ownership, management, and event hosting may involve multiple parties.
  • For Premises, the responsible person is the individual or entity that has control of the Premises in connection with their use. Where a Premises has more than one use, responsibility rests with whoever controls the Premises in connection with the principal use.
  • For Events, the responsible person is whoever has control of the Premises at which the Event will be held for the purposes of that Event. This determination will depend on the specific circumstances of each event and the terms of any event agreement. The key question is: who has control of the event area?
  • Where the responsible person for enhanced duty Premises or a qualifying Event is not an individual (for example, where a company or partnership is responsible), it must designate a senior individual with responsibility for ensuring compliance with the Act. In the case of a trust (where the trustees are the responsible persons), if the trustee is a corporate trustee, it would need to designate a relevant senior individual. If the trustees are natural persons acting jointly, they are already individuals and this requirement may not apply in the same way although this is not clearly addressed in the Act.

REGULATION AND ENFORCEMENT

The Security Industry Authority (SIA) will regulate compliance with Martyn’s Law. The SIA intends to adopt a supportive approach, providing guidance and assistance to help venues meet their obligations. Where there are serious or persistent breaches, the SIA has enforcement powers including the ability to issue compliance notices, impose monetary penalties, and issue restriction notices. The Act also creates certain criminal offences for the most serious failures.

The SIA will publish statutory guidance on how it will discharge its regulatory functions. The 24-month implementation period is designed to allow time for the SIA to establish its new regulatory function and for those with responsibilities under the Act to understand their obligations and prepare accordingly. Although the SIA’s statutory guidance has yet to be published, in November 2024 the Home Office published the “Terrorism (Protection of Premises) Act 2025: Martyn’s Law Myth Buster. A copy of this document can be found at martyns-law-mythbuster.pdf.

PRACTICAL STEPS FOR HISTORIC HOUSES

Those responsible for Historic Houses should begin preparations now. The following steps provide an initial framework from which to start to think about compliance with the Act.

Assess your position

Determine whether your premises or events meet the 200-plus expected individual threshold. If so, identify which tier applies: Standard Tier for Premises with expected attendance of 200 to 799 individuals, or Enhanced Tier for Premises or Events with expected attendance of 800 or more individuals.

Standard Tier compliance

Provide terrorism awareness training to all relevant staff, contractors, and volunteers. Develop and maintain a basic preparedness plan covering how to warn people, initiate a lockdown, evacuate the Premises, and contact emergency services. Ensure all personnel understand their roles and responsibilities in the event of an incident.

Enhanced Tier compliance

In addition to Standard Tier requirements, conduct a detailed risk assessment and submit this to the SIA. Develop a comprehensive security plan and implement additional security measures as required. Maintain records of training, plans, and drills, and review and update these regularly.

Ongoing obligations

Engage with the SIA and follow their guidance. Be prepared for inspections or compliance checks. Communicate plans to all staff, contractors, and volunteers, and incorporate these into inductions and event briefings.

HERITAGE-SPECIFIC CONSIDERATIONS

Historic Houses present unique challenges for security planning.

Lockdown procedures

Heritage doors and locks may not operate as quickly or reliably as modern alternatives. Practice rapid locking procedures and ensure keys are readily accessible. Identify secure rooms that can keep people out of sight in an emergency.

Evacuation planning

Historic buildings often have non-standard layouts that can complicate evacuation. Map all exit routes carefully and verify they are clear and functional. For Events, consider using temporary signage and deploying stewards to guide people away from danger.

Communication

Check mobile telephone coverage across the estate and identify areas with the best signal. Consider providing shared radios for rapid communication across the property particularly where there is weak mobile phone coverage and there is a risk that wi-fi networks may go down in an emergency.

Warning systems

Where public address systems are limited by heritage constraints, pre-position megaphones or radios at key locations. Identify audibility gaps, particularly in wings, gardens, and outbuildings, and plan how to address them.

Access and coordination

Brief all teams—including those managing gates, parking, and the wider estate—on how to warn visitors, initiate lockdown procedures, and direct evacuees. Consider the potential impact on neighbouring premises and shared access routes.

Events and changing use

Integrate security planning into event management processes. Ensure contractors, caterers, and others working in temporary structures such as marquees are briefed on procedures upon arrival.

REVIEWING EVENT AGREEMENTS

Those who hire out Historic Houses for events should review their existing event agreements and precedent documentation. It will be important to establish clearly which party bears responsibility for compliance with Martyn’s Law and to ensure that agreements address the allocation of security obligations between the venue and event organisers. Understanding who will be responsible for what is essential to managing risk and ensuring compliance.

CONCLUSION

Martyn’s Law represents a significant development in the regulation of public venues and events. For Historic Houses that welcome visitors or host functions, the legislation introduces new obligations that require careful planning and preparation. The 24-month implementation period provides an opportunity to assess exposure, develop appropriate procedures, and train staff. Those responsible for Historic properties should use this time to ensure they are ready to comply when the Act comes into force.