Following the bifurcation of the thread into the realms of car & tractor engines: as a long ago owner of a TR3A, my understanding of the engines of the TR2-3-4 series is that they were derived from a Ferguson tractor engine. Whether the same engine went into the Vanguard, I don't know. But Triumph and Standard were not in the same group of engineering companies, were they?
(With apologies for continuing the drift!)