I had been a bit worried by how non-commital and unenthusiastic he sounded on the phone.
Now the penny has dropped.
He’s a teenage boy and there were other people in the room.
Yesterday I had a proper talk with him and, apart from really missing us (a good thing), he’s thoroughly enjoying himself. And he was ringing to see if he could go out for the weekend to the home of one of his new friends who’s a weekly boarder (and who, conveniently, lives just across on the other side of the Solent).
Apparently he was going to write me a letter yesterday evening during prep, as he had no homework to do. Now, should I hold my breath in anticipation?