Q. Over New Year I stayed with a man who combines being a generous and exciting host with a punctilious need for swift, hand-written appreciation. I had every intention of writing as soon as I got home, but my parents said an email wouldn’t do. However, since we were collected from the airport I didn’t have the address and postcode (he lives abroad); also, I didn’t know what his correct title was for the envelope, and I didn’t know what stamp to put on.