Finding a good example of a Brummie accent as proven more tricky as I'm either stumbling across paradises where they over accentuate the "twang", or TV personalities where the access is suppressed a little. Ozzy Osbourne is from that area and in his interviews you can sometimes hear the accent showing through. The pronunciation itself isn't hard to understand; I highlighted it because it's a unique accent. I think these days it's mellowed quite a bit though.
This video isn't work safe, but it's the best example of a Welsh accent I could find. https://www.youtube.com/watch?v=HwUrMEZWj5o (this is also probably the accent I hate the most - I couldn't explain why, but it just grinds)
This is the Cornish (south west) accent: https://www.youtube.com/watch?v=8jbxdZE3g80 It's probably the closest to the old Shakespearian English that someone linked to in these comments.
For the non-English readers, the two girls are Welsh, the two boys are from (if I recall correctly) south Essex (a suburb north of London).
Sunderland is about an hour away from newcastle.
EDIT: Oh gosh and there are some amazing clips from a local radio phone in show in norwich here: https://soundcloud.com/voices-of-norfolk/sets/radio-norfolk-...
This lady is particularly endearing: https://soundcloud.com/voices-of-norfolk/nancy?in=voices-of-...
Here's a recording of market traders in london with cockney accents, and some jamaican I think: https://soundcloud.com/london-sound-survey/brick-lane-market...
That soundcloud account is full of field recordings taken in london, lots have distinctive voices in them: https://soundcloud.com/london-sound-survey/wembley-cheapjack...
> Sunderland is about an hour away from newcastle.
Not even that. Newcastle and Middlesbrough are about an hour apart (just down the A19); Sunderland is less than half the distance away.Occasionally you'll find extras which sound Welsh, because the show is filmed in Wales. But for the most part it's a very neutral accent. Even Amy Pond's accent isn't particularly strong.
As well as the accent there is the question of the brummie dialect which can be much harder to decipher for a non native "yow" for "you" for example
Here's an interview with some of it's stars: http://www.youtube.com/watch?v=8fLiVKNuzjE