Actually, the classical British accent (generally referred to in artistic circles as the "Shakespearean" accent) favors vowel sounds that are pronounced by raising the soft palette and lowering the larynx... exactly the sort of muscular actions singers have to train themselves to perform, so they can properly modulate their voices.

In a sense, the accent they're born into and use all their lives make them natural singers, even when they're just trying to get a point across.

Of course, that's assuming he actually was born into a family that pronounced everything with that accent. It's actually pretty rare, even in Britain, compared to the number of people who consciously train their voices that way.