For whatever it's worth to anyone, there essentially was no such thing as a Lucas sealed beam headlamp for the US market until maybe around 1964. For the most part, Triumphs built for the US market were shipped without any headlamp units, which were then installed stateside, probably either by the regional distributor or the selling dealer. So a true "original" headlamp in an earlier US-spec. Triumph really should be a period Sylvania, Guide, Tung-Sol or GE unit!