The Security Industry Authority in London regulates event security services (SIA). In the UK, the SIA is in charge of overseeing the private security sector, which includes event security services. As a result, event security firms operating in London must maintain current SIA licenses for both their security agents and themselves.
A risk analysis and an emergency plan for the event should also be available from event security services in London. According to the size and nature of the event, they should also be able to supply enough security staff. The onus of ensuring that the event security services they hire abide by SIA guidelines fall on the event organizers.