Britishmade casing but the mag housing, looking at the underside is so bad, even by Sten standards, that I think that it is Pakistani. No markings underneath and just look at the size of the rectangular slot for the mag catch to go through. The catch would be a totally sloppy fit - as would the magazine! Or as we would say, like throwing a sausage down the high street........, although I don't suppose that they throw many sausages in Pakistan! That mark on the breech block is a crown on its side
Just my 2p's worth