I wouldn't carry this line of argument too far. I can't speak to Thatcher's vulgarity, especially in private, but she could be devastatingly effective in delivering a put-down. Just watch some of the old Question Times in the House of Commons (or whatever it was called when the PM had to respond to any questions they had.) I can't recall any cursing offhand, but she could be very blunt, and occasionally salty. Her behavior was not "lady-like," it was appropriate for a Prime Minister.
Cursing is more common here than it is in England, as well. It is appropriate to criticize Clinton for losing her temper, but the language - not so much (OK, it's appropriate to criticize her for anything, I'm just trying to be fair here...)
Drew Garrett