I live in Lincolnshire, a large county on the east coast of England, and after ten years of being here, I can distinguish a native of my town of Louth from one of Cleethorpes, 15 miles away. 35 miles south of here, in the original Boston, the local accent is rather different again.

Most Brits would not notice the difference as Lincolnshire accents are broadly unrecognized nationally, though any Brit (and, perhaps, many Americans?) could distinguish a Scouse (Liverpool) accent from a Mancunian (Manchester) one - only 27 miles apart. Think Beatles vs Oasis here.

Sadly, though, this does only work on true, thoroughbred natives - a small percentage of the population in most areas now due to the frequent movement of people around England.

It's funny how exact opposite Australia is. You can travel from Perth to Brisbane - 4 times the length of the UK - and even locals can't tell the accent apart from their own. There are differences, but they're not based on region.

"City" I'm in is within 10 miles of the next city and it's quite popular to make fun of each others different accents and propensity for certain dialect.

I do love it when you listen to someone talk and you can hear where they're from; occasionally I can do a Henry Higgins (http://en.wikipedia.org/wiki/My_Fair_Lady) and hear the overtones of where they moved on to as well. A strange delight.

The town where I grew up has a couple of dialect words that are only spoken by the working class in the environs. Fascinating stuff.

A few hours cycling is nothing - when I grew up in the North East of Scotland people from the coastal fishing villages had quite different accents to people from farms maybe 1 km or so inland.

[NB When the BBC did a TV series featuring fishermen from near where I grew up they had to give the show subtitles so it could be understood in the rest of the UK ;-)]

http://en.wikipedia.org/wiki/Trawlermen_%28TV_series%29

It's a sign of stability. The US was recently (in linguistic timescales) formed. There was also a lot of migration within it. The population of UK cities may have been (largely) stayed put for centuries.

Jared Diamond uses this a lot, when trying to unearth the history of populations. This isn't a new thing - the 1956 Kurgan hypothesis suggests that PIE (the language which everything from English to Indian languages descended from) is a sign of a large empire, or a dominant culture which expanded across Europe. It suggests PIE may come from the Russian steppes, and that their secret weapon was the domestication of horses (due to the prevalence of "horsey" words in PIE). Diamand uses similar logic to trace the expansion of other cultures.

For contrast, New Guinea has lots of of languages, as until recently it has been very divided culturally and politically. Many villages were pretty much their own state.

There's actually at least one place in the U.S. which is like this -- the Boston area. I once saw video of sixteen Bostonians speaking, each with a slightly different accent; a trained ear would be able to narrow the accents down to a neighborhood or even particular street, and make guesses as to the speaker's socioeconomic status.

Boston really is "closest to England" in a lot of ways.

Same here in The Netherlands, I can tell if someone's from one or two towns away by his/her accent. It's subtle, but definately noticeable providing they speak with an accent. A lot of dutchmen learn to speak accentless, or Standardized Dutch but resort to their native accent when in familiar surroundings.