Very true. Richards' accent is decidedly southern, as his family settled in the London area after leaving India when he was young. That is the way he pronounces such words in his normal speaking voice.
And yes, a lot of the most successful British music has come from the northern cities, where the accents are very different. I seem to recall some pop group that made an impression some years back who were influenced by American music coming into the seaport of, oh, was it Liverpool?