Summary Offences Act 1953

If the owner of any property, or the servant or agent of the owner of any property, finds a person committing an offence on, or with respect to, that property, the owner, or the servant or agent, may apprehend the offender and deliver the offender as soon as reasonably practicable into the custody of a police officer to be dealt with according to law.

In this section—

owner, in relation to property consisting of land, a building or other premises, includes an occupier of, and a person resident on or in, the land, building or premises.