Don’t get your knickers in a twist, mate! I know that technically, there is no such thing as a “British” accent. But what else would you call the English-ish dialect that’s long been used as a catchall in American-made movies and TV shows set anywhere ancient, foreign, and/or magical?
The fantasy thing, at least, makes a certain amount of sense. That genre has its roots in stories like J. R. R. Tolkien’s Lord of the Rings saga and C.S. Lewis’s Chronicles of Narnia; naturally, those authors’ homelands (and, therefore, their way of speaking) are associated with the stories their work has inspired.
Perhaps more importantly, made-up fantasy lands tend to have cultures and customs based at least partially on those of medieval Europe — and even if people in medieval Europe didn’t sound remotely like denizens of present-day London, using modern British inflections makes fantasy characters’ speech sound more authentic to most people’s untrained ears. Hearing knights and princesses speak like they were brought up in Cincinnati just seems wrong — possibly also because the United States has existed for only 237 years.
That last reason is probably why most TV shows and movies set in the real world’s past eschew American accents for British ones. (Except when they make the bad guys British and the good guys American. See also: Disney movies.) There’s even a term for this trope: The Queen’s Latin.
Why, though, should the warring Greeks and Trojans in Troy all sound vaguely English, even though England wouldn’t exist for over a thousand years, Troy is located in what’s now Turkey, and Greece is, you know, Greece? Why do the titular miserables in Tom Hooper’s Les Mis musical speak and sing with crisp British diction, even though the movie takes place in 19th-century France? The CW’s new period soap Reign is set in France as well, inhabited by characters from a variety of 16th-century European backgrounds… yet the Dauphin Francis, Mary, Queen of Scots, and her Scottish ladies-in-waiting all have the exact same British accent. Sexy Nostradamus, though, speaks with actor Rossif Sutherland’s native Canadian cadence. (Side note — he’s Kiefer Sutherland’s half-brother! Weird, right?)
Obviously, authenticity isn’t exactly a top priority when you’re talking about something that features Sexy Nostradamus, or a bunch of Parisians who communicate through song, or Brad Pitt being murdered by Orlando Bloom. I also get that when a film or show’s cast is made up of English-speaking people from various backgrounds — American, British, Canadian, Australian, etc. — an accent mandate may be imposed to make everyone sound like they’re coming from the same place.
That said, it’s still an irritating convention — and there’s no good reason why “British” should always be the default. Is there some unfounded assumption that non-English people can handle English accents more easily than French ones, or German, or Greek? Instead of forcing actors to do an accent that makes absolutely zero sense in context, why not just let everyone use their normal speaking voices and trust that the audience can suspend their disbelief? (That’s how it works in Les Mis onstage — Filipina actress Lea Salonga did Eponine without an accent, and she sounded juuust fine.)
Say what you will about Lifetime’s ridiculous Donatella Versace biopic, but it was refreshing to see a bunch of Americans and Canadians playing Italians… and actually trying to sound Italian. Sure, their attempts ranged from fairly decent to Super Mario Bros… but sometimes, it’s the effort that counts.