Well, according to my totally legitimate sources (Wikipedia, lols ) All forces have "had access" to them since 2004, but only issued to AFOs (Authorised Firearms Officers), so chances are, the local force has seen no use for them or you just never seen a Firearms Officer (and fortunately so)
I forgot his name but somebody prank called the police and told them they were in possession of drugs. Turns out, the streamer and his girlfriend were actually in possession of drugs.