On The Tudors, why does the Earl of Surrey have a Scottish accent? Isn’t he the son of the Duke of Norfolk? (Although the two seem to be about the same age as portayed on the show.) Did they just not bother finding an actor who could sound English?
I’m guessing that’s about it. It wasn’t like that series was a paragon of accuracy in other respects ;).
Presumably only because the actor who played him as an adult is from Glasgow. 
Keeping all those Howards & Seymours straight kept my head spinning throughout the show. You are right though, he was the son of the Duke of Norfolk (who was also Earl of Surrey), but the Surrey titled passed to the son by courtesy to provide him a title.
http://tudorswiki.sho.com/page/Henry+Howard%2C+Earl+of+Surrey
For some reason, this one thing especially confused me. Somehow I couldn’t separate his Scottishness from his character, especially with his involvement in military actions in Scotland.
Especially since half the men are named “Thomas.”
And the women are all Mary or Catherine?