McGrath thanks for the link, I worked with people from all over England hrow in a few Welsh and Scottish accents and I would say the most incomprehensivle was the Newcastle on Tyne and the midlands accent.
It took me awhile to get around the Geordie and Wolverhampton lingo but moving around through the various English counties gives you an ear for any accent, and my favourite has to be the Suffolk accent. Ard Mhacha.