Re: British revenge
Actually, "But all I can say in us Yanks' defense is that you Brits" is clunky but correct, and "All I can say in defence of we Yanks is..." is incorrect. What the OP should have said is, "But all I can say in our defense" for better flow, but grammatically his use of "us" is correct.
Grammar rules found here: http://snarkygrammarguide.blogspot.com/2012/09/object-of-preposition-all-of-us.html
For me, the easy way to tell is to remove the noun from the prepositional phrase and see how it reads.
Ex: He has no trust in us scientists.
Correct (with "scientists" removed): He has no trust in us.
Incorrect (replace with "we" and also with "scientists" removed): He has no trust in we.
So if the sentence sounds correct with the noun removed, you have the correct pronoun.