The main thrust in Britain came in about 1840 when following their enormous success in America the first troupes came over here and were equally an enormous success. (Think The Beatles)

Apologies Steve if I'm being a bit dim, but I don't really understand The Beatles reference. Presumably you're thinking of the '64 'American Invasion' and their re-exporting Black American music?

I can't get the analogy though. But I'm really tired this evening...