Shortly after I wrote that got an email from Amazon to say they were shipping it 2 days earlier.
So what can I say here, that will make them ship it NOW?
Just have to say it - this is a magic thread.
Today, 6th Feb, Amazon sent an email to say my book has shipped. Now since their previous email said "estimated delivery date 13th Feb" (which was two days earlier than 15th Feb as originally promised), all I have to do now is hope Royal Mail doesn't take seven days to deliver. I could be tempting fate by writing that here.
(Especially good if it could turn up during next week, since I've got days off and can sit and read by the hour.)