Luty 9mm SMG
The original "Can’t stop the signal"
Designed (and built) in a shed in Leeds by a man called Philip Andrew Luty.
It’s unrifled and has no sights, expect poor accuracy and limited range (sub 50m)
I had trouble getting info for this one (the books being VERY illegal in the UK) so I just had to guess a lot, go on what Grok says and feel the general vibes that I could get from the videos on youtube.