Britishisms and the Britishisation of American English

The BBC tells us that while English English is adopting Americanisms there is a more discreet flow of words in the other direction. 

So odd what words we do not have in common. A word as common as fortnight is not known over there. An American once asked me what 'twee' meant and I said:

And 'Tea' she cried, in a tiny voice,

'Wake up! It's nearly FIVE!'

Oh chintzy, chintzy cheeriness,

Half dead and half alive.

I usually resent Americanisms used by Englishmen and have taught a score of Romanians to pronounce the first syllable of schedule as if it were shed. One young American battleaxe I am delighted to say got cross with me when I told her that and said shrilly

'Nobody speaks British English any more!' 

'Well, sixty million people in Britain do, I suppose.'

I told Romanians to use the word 'frightfully' instead of 'terribly' if they wished to irritate Americans, which they did indeed want to do because they are all snobs and think American English is vulgar. (Saul Bellow taught me that Americans are annoyed by 1930s British expressions used by foreigners.) I especially hate alumnus or, even worse, alum. What is wrong with saying 'Oxford men and women' or whatever? But I nevertheless admire and love the fecundity of American English: fuzzy maths; bimbo eruptions; babe hoover; user-friendly; spin doctors; couch potatoes.