Several members of the LAPD shooting team in the late '40s and '50s made custom stocks that were similar in design. I believe Walter Stark was the first one to produce them, then Blackford, Farrant, Hogue and Hurst (and maybe others) came along after.
I agree the stocks under discussion here don't look quite as finely finished as other Farrant sets I have seen, but I wouldn't rule him out as the maker.