I can’t disagree with a word you’ve said. This is really an issue on the show, lets hope that the new head honcho redresses the balance during his tenure.
Maybe the posh accents are a reflection of house prices, I have done a very quick google search and the average house price in Warwickshire which I picked as a sort of Ambridge place is about one hundred thousand pounds more expensive than in Birmingham. So your average Brummie wouldn’t be able to afford to live there. It’s a theory.