English accents in Fantasy

Interesting thing on the BBC today about English (or British if you include the Welsh and the Scottish) accents in fantasy.

I cannot help but write in an English accent with all its slang, but I wonder if readers abroad read it that way? I've always thought of the other accents in The Fireblade Array world as sounding Italian, French, Japanese or Russian, but strangely never North American or Australian.

Silly really, since Aussie came from the estuarine/East London accent, and (broadly speaking) North American accents aren't far-removed from Western Irish and old English. So, rather than asking "Why British?", why is it that TV adaptations or films on fantasy tend to avoid North American, Aussie and South African accents? Is it some deep-seated association with colonies? Is it to do with our view on mediaeval history and who was in it?

I think it just goes to show that no imaginary world is understood in isolation from our own perspectives on this one. This is hardly a new observation, but I suppose it can actually offer film makers and writers greater freedom in playing with some existing cultural assumptions. I have to agree that it's good to see English accents not reserved solely for 'the bad guy'! And it's a nice way of illustrating distance or social boundaries by using existing parallels, e.g. having Yorkshire accents vs southern.