Indeed. Although of course, we don't know exactly what happened on the day. It could have fallen on the floor and he picked it up and put it in his pocket intending to throw it in with the melt, forgot about it. Then decided to keep it for posterity. Maybe later gave it to a young relative as an example of a silver threepence. Of course, in 1945, he'd have had no idea of its future worth.
I bet it will fetch many orders of magnitude more than £4k this time.