"Long Branch" was never a company, "Long Branch" was a facility OPERATED by "Small Arms Limited" (a wartime Crown Corporation), on Dec 31, 1945 "Small Arms Limited" passed control of the Long Branch facility to CanadianArsenals Limited (a post war Crown Corporation) on January 1, 1946 which then operated the Long Branch facility as "Canadian Arsenals Limited, Small Arms Division", a sister division to the Canadian Arsenals Limited, Explosives Division and apparently few others.
Small Arms Limited didn't cease to exist on Dec 31, 1945, it continued to tie up its operations until mid 1946.
Oh yeah, Long Branch, and EAL serial numbers are on the LEFT side of their receivers.