It COULD be, but the RAF spring loaded No7 single shot platform that we have here is much different. Maybe the one shown by Warren was for the limited production/trials No5 by BSA.
BSA really wanted their rifle to be adopted. After all, a similar rifle had already been adopted by the RAF. But the MoS convinced the Army that the Enfield designed .22" rifle was the best and it could be manufactured at the rifle plant at Fazakerley too. BSA could also make them to speed up production and placate them for rejecting their offering. BSA output stripped Fazakerley but after the contract ended, because they simply made them on a MoS contract, they were forbidden to continue production or make them for other customers.
The story goes, as told to me by an Ordnance Major (Major Rees at the huge NDOD) while in NZ, that due to a slight contractural misunderstanding or oversight, BSA bid for the NZ requirement for a new .22" trainer and built the NZ DA contract - hence the DA serial number prefix. Naughty, naughty. It would have just passed unnoticed for many years until the NZ Government went to the MoS for spares several years later - who queried how they had them when there had been no outside sales or disposals...........