The pronunciation of "Gloucester" (gloster) and "Leicester" (lester) follow a similar scheme for the "-cester" bit which leads to "Worcester" being pronounced "wooster", but Worcestershire sauce is often pronounced "wooster sauce" which doesn't make much sense.
Apparently, Frome in Somerset is one of the hardest place names to pronounce in England, though it certainly doesn't compare to some Welsh towns. (I say it as "froom")
Worcestershire and Worcester follow the same patter as Gloucestershire/Gloucester, Leicestershire/Leicester and (Towcestershire doesn't exist)/Towcester. Towcester, incidentally, being the same pronunciation as "toaster".
The one that annoys me is Cirencester, which is usually "sai-ren-ses-ta", and only occasionally "sai-ren-ster".
Or, according to my grandmother, "siss-iss-ter".
It sits on the River Nene, which is pronounced Neen or Nen depending on which bit of Northamptonshire you live in (Northamptonshire is not very big...)
"That's just incorrect. It's pronounced "wooster-shuh". The double-O is short, as in "book". Worcestershire Sauce is sometimes simply called "woosters", as in "a dash of woosters".
> Frome in Somerset is one of the hardest place names to pronounce
Hardly. It's pronounced "froom". That's not so hard.
I agree that it's not tricky to pronounce, but the difficulty is pronouncing it correctly.
Worcestershire sauce can be called "wooster-shuh sauce" or "wooster sauce" or as you say, "woosters".
Bad example, since some accents pronounce "book" like "kook" (not like "suck") ;)
Also, this scene from Archer cracks me up: https://www.youtube.com/watch?v=_4jxLxZrMfs
And there's a Gloucester[0] (pronounced 'Gloster' or, more likely in MA 'Glostah') there as well. And there's one[1] in Virgnia too, (Wikipedia says it's pronounced 'Gloster', but I don't know the VA accent well enough to know if that's locally correct).
There are other similar place names around the US, mostly on the eastern seaboard, for obvious reasons, as well.
[0] https://en.wikipedia.org/wiki/Gloucester,_Massachusetts
[1] https://en.wikipedia.org/wiki/Gloucester_County,_Virginia
(Many words place names long pre-date any kind of attempt to regularize English spelling, and in any case come from fusions of Brythonic, Norman, Roman, Norwegian etc languages. This is why it's difficult to predict the pronunciation of one word from the spelling of another.)
Someone asked about physic ... well people used to use physick in [late medieval?] British English... but that's for what we might call medicine now.
Map men explain it best.
That is at least the theory I've heard