How come Quartermass has no British accent?

Brian Donlevy was hired to give the movie "marquee value" in the US (and even in Britain), as he was a familiar star with a recognizable name as well as a solid, respected actor (Oscar-nominated in 1939 for Beau Geste). I don't think there was ever any intention of passing him off as English, though his nationality is never mentioned.

Hiring American actors for British-made films was not uncommon in the 1950s (or now, for that matter). At that time, Americans who worked abroad for 18 months straight could avoid paying income taxes on any money earned, and since the applicable rate for top stars with the highest earning power was 80%, many of them took advantage of the law and made films in Europe and elsewhere. (It was later repealed and everyone who had benefited was retroactively charged for his or her taxes!) Major films featured big box office names, but small studios like Hammer could not, of course, afford such people, who in any case weren't likely to be attracted to medium-budget sci-fi movies anyway. But the operating principle of getting someone whose name would mean something to audiences, and would dress up the movie, remained, as did any tax incentive. Thus, people like Brian Donlevy, Howard Duff, John Crawford, Forrest Tucker, Dean Jagger, Gene Evans and others made one or more such films in England. None of them was ever depicted as English, and some were explicitly expatriate Americans in their films.

I thought Donlevy was quite good and appealing in his two turns as Professor Quatermass, but then I always liked him as an actor. Andrew Keir was excellent in Quatermass and the Pit/Five Million Years to Earth, but then that was a decade later and with a somewhat different interpretation of the character written into the script and extracted by a different director.

(By the way, it's Quatermass, with one "r" (not "Quartermass", as the thread's title had it originally -- now corrected).