Aerohack:
There's a good precis of the "two nations divided by a common language" quote at
http://www.miketodd.net/encyc/lingo.htm , which is in any case well worth a browse. The site's run by one Mike Todd (nah, get away), BBC Radio 4 duty manager, whose masterly exposition of the etymology of "OK" on the same site has achieved canonical status (well, it was quoted by Melvyn Bragg).
R