Thanks for your kind words, everyone! I couldn't enter the best dressed competition as my company hosts the event; myself and a colleague pretty much organise everything between us. But I did get a few people saying I should have won!
I wore the collar pretty much all night - except for when we went out afterwards as I didn't think I'd get into the pub with it on.
It was very comfortable to wear, except in one spot where I hadn't trimmed back one of the feathers enough. And also very stable - it attached to the dress with the front wires slipping into a channel in the dress, and two pieces of elastic in the back with snaps that attached to snaps on the inside of the dress. I expected it to feel very flimsy but it was quite the opposite, and easy to wear!