Clause 21 provides a power for immigration officers to seize anything they may find in the course of exercising a function under the Immigration Acts while lawfully on the premises where they believe that it has been obtained in the consequence of committing a crime, or where it is evidence of an offence. They may do so only in order to prevent the item being concealed, lost, altered or destroyed and may retain it unless a photograph or copy is sufficient. Again, this is similar to the example of the mobile telephone seizure that I gave in the debate on clause 19.
Immigration officers sometimes encounter evidence of other crimes when they are searching premises using immigration powers. In such circumstances they will contact the police and, if necessary, wait for police to come in order to secure the evidence. In the meantime, the problem is that immigration officers have no specific powers to prevent other persons on the premises removing, altering or destroying the evidence before the police arrive. It makes sense that immigration officers who are trained in securing evidence should be able to seize it to ensure that this mischief does not happen.