***** NOT A TEACHER *****
I have just read this in the May 24, 2012, issue of the London Review of Books:
"He's [an author] modest, aware that a modern Brit [my emphasis] cannot easily grasp what it means to live among
changeable frontiers, ..." [He had written a book about the history of East Prussia.]
*****
Thanks to all the wonderful posts, I have learned:
Non-offensive:
A British person.
A Brit.
A Briton.
Offensive:
A Britisher.
A Limey.