Hi, Tried a few in London, and generally you get a great massage in Everwell in Gerrard St, Chinatown. The girl there, Jenny is in her 30's with a model body. She does a proper massage - very thorough and then giggles a bit when she asks if you would like "this bit massaged too" She will strip for £20 and let you explore all her "avenues" Only criticism is her HR (or is it HJ) she tended to pull it around as if it needed to be shaken violently awake!
The one in Little Newport Street is a bit of a fleapit, the women practically pull you in, and it's a dive. Best avoided.
There are two of three down the sidestreets near the tube in Earls Court that do the business, and they are more discreet than the Chinatown places.