Law Enforcement (Powers and Responsibilities) Act 2002

One of the persons executing a warrant must, before any of the persons executing the warrant enters the premises—

announce that the person is authorised by the warrant to enter the premises, and

give any person then in or on the premises an opportunity to allow entry into or onto the premises.

A person executing a warrant is not required to comply with this section if the warrant is a covert search warrant or if the person believes on reasonable grounds that immediate entry is required to ensure the safety of any person or to ensure that the effective execution of the warrant is not frustrated.