Well I don't want to drag it out so here's a big clue, it has the same name and was no doubt named after a city in Yorkshire, England; that is well known for it's ethnic diversity. This city was also the place of it's manufacture, don't forget the radiator badge has been cloned out (badly). You must get it now?
the only one I can think of that is vaguely connected to Yorkshire is Humber, but that's not a city and was built in Coventry.
edit: there was also marque called Sheffield something or other but that is too old if the Hillman was too old.