Question Author
Hello, John Alex, and many thanks for your reply and encouragement.
In a way it's reassuring that answers haven't flooded in - at least I don't feel like I've missed something very obvious!
I did a search on AnswerBank before asking my question and found the question from years ago and still with no answer, but I've read through everything which came up again (obsessional, or what?!) and found amongst the listings a suggestion of 'Christmas stamps', which does seem to fit.
Again, many thanks, and at least I've been brave enough to post a question so might become more involved in the site in the future. (Plus I can get rid of this irritating quiz at last!)