looks like a jhob for jheem and his bag of magic IPAs!

Thanks, AS. Here it is in SAMPA and IPA (in case the latter doesn't work for you the former should):

/'bO:st@n/ SAMPA Boston in MA

/ˈbɔstən/ IPA Boston in MA

/'bQst@n/ SAMPA how you hear some people from Boston, MA, pronounce Boston

/ˈbɑstən/ IPA for the same

The local pronuciation of the first vowel is a tad bit lower in the local than in the standard USan version. Boss I usually pronoucne /'bO:s/, but in A-H an alternate pronuciation is /'bQs/. The /O:/ is what you all have been writing as {aw}, but which is not a diphthong, it's longer and that's why it has the colon in SAMPA which is like the IPA for macron. (NB, there's no {L} in the IPA transcription because, as it is broad and there's no phonemic distinction between /ɔː/ and /ɔ/, i.e., /ɔ/ -> [ɔː]) It's sort of like the distinction in the US between caught and cot, if you make that distinction, which I do and so do the nice folks up in Boston, MA. If you can play WAV files, the A-H provides pronuciation (at least of the first and more common pronuciation).

Haven't a clue about Boston in Lincolnshire, either RP or local dialect. What's all the hubbub?