I agree with what has been written by other members so far.

Just did a LHR-HKG on BA First Class last week. It was quite cold during the meal service, but became uncomfortably warm afterwards. The F cabin was very stuffy and warm, and it's the first time I have been unable to sleep on an evening flight.

Forget the duvet - I didn't even try it - the temperature was so uncomfortable I couldn't even put the blanket over myself. I gave up sleeping after an hour wriggling and writhing in my bed (which is, I must say, not that comfortable when you compare it to CX/SQ) and ended up watching movies for the rest of the flight.

I had a little walk down to the C and Y cabins, which I found were cooler than the F cabin .... which probably explains why I have been able to sleep in C and Y in the past. I didn't expect to arrive in HK without a minute of sleep after a 12 hour flight !!

As the C cabin was basically empty (all C passengers were given upper deck seats, and the main cabin was empty) I asked the F purser if I could try out the C seats (although I've been in them before) .... and it was much cooler and comfortable. Ended up watching a movie in the C cabin, while dressed in the F sleepsuit and hugging the thick duvet. The F purser was nice enough to pop into the (empty) C cabin from time to time to make sure I was alright.

Should I have explained the reason for doing this (F is too warm!), instead of making up the lame excuse (I want to try your CW seat .....)