CI5 hq

Hum. The US-oriented Merriam-Webster dictionary lists the warm-scarf meaning first. There is no suggestion that it is a Britishism. Perhaps it is used in some part of this country that I've never lived in, or perhaps it was formerly common here but is now dated. I will ask my mother what she thinks.

It does indeed appear at least twice in A House at Pooh Corner (1928):

"So what I'll do," said Pooh, "is I'll do this. I'll just go home first and see what the time is, and perhaps I'll put a muffler round my neck, and then I'll go and see Eeyore and sing it to him."

The clock was still saying five minutes to eleven when Pooh and Piglet set out on their way half an hour later. The wind had dropped, and the snow, tired of rushing round in circles trying to catch itself up, now fluttered gently down until it found a place on which to rest, and sometimes the place was Pooh's nose and sometimes it wasn't, and in a little while Piglet was wearing a white muffler round his neck and feeling more snowy behind the ears than he had ever felt before.

I think this is the context in which I first encountered it, which is probably why I think of it as a British word. Could be that it is just an unusual word.