Very few Lanchesters here (USA) in usable condition, Peter.
I am guessing this is from a Mk1? Aside from the markings, there's no screw hole for the barrel screw.
https://www.milsurps.com/images/impo...rmagwell-1.jpg
I don't have the $$$$$ for a registered STEN receiver, so it will be resurrected as a semi-auto only SBR.