Tell ya what ya wanta do, Steve: Rhythm and blues, like Soul came out of the gospel groups singing in black churches. That basic four-part harmony is still being sung in many black churches. Admittedly, some of the larger churches are into Mass Choirs and have a whole battery of guitarists, organists, pianists, drummers and keyboard players, but many black churches still have a smaller group that sings regularly. This Sunday, my quartet is singing at a concert in a store front church in New Haven, CT. There'll be several small groups singing there from area churches. I've written gospel for my group, and some of it has harmonies and chord prgressions straight out of old rhythm and blues... In The Still Of The Night, and The Great Pretender. The white gospel quartets, called "Southern Gospel," are more barbershop quartet grounded. They'd be fun to sing in, too, but I love rhythm and blues more, so I prefer the black gospel sound.
All this said, from what I hear from my friends in England, there may not be a lot of black churches in London. I only spent one day there, four years ago, so I wasn't seeking out black churches. But, there's a fine tradition of harmony singing in England, so there must be people somewhere who want to sing together. Just hard to find them...
Jerry