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.
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).
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
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.
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.