I don’t know.
Maybe the “miniature rifle” exemption in the Firearms Act 1968 (as amended)? Which is maybe soon to be changed, because it was designed to cover fairgrounds with .22” single-shots, but a couple of idiots recently used it to set up ranges which - legally - allow anyone to use semi-auto .22LR AR15 and AK lookalikes and then put scary-looking “terrorist training” videos on the internet that were picked up by the Daily Mail?
I can attest that with the fairground full-auto guns it is nearly impossible to shoot out the star. I have tried many times over the years. Any other shooting fairground game, even cork-firing Gat rifles, I can usually win a small stuffed toy. The machine gun things, never. Sometimes close, but no figurative cigar.