There was a to-do over the Windsor coat (what looks like a dinner jacket with scarlet or red collar and cuffs) on AAAC and SF and probably LL too, back some months ago. 

You can see a pic. and description of the Windsor coat here:

http://en.wikipedia.org/wiki/Windsor_uniform


Apparently though, the wikipedia article isn't very accurate, and those discussions back then should be emended to include
new information published recently.

Stay tuned for excerpts from John Rogister's TLS review of the fascinating book by Philip Mansel, <<Dressed to Rule:  Royal and court costume from Louis XIV to Elizabeth II>>