A week after finalising the sale of my old house, I realised there was a key I'd forgotton to pass on to the new owners. It was only an old-fashioned generic key, but  the sense of closure inherent in divesting myself of it appealed to me. When I went to see my selling agents for the last time, however, I forgot all about it. I hugged the agents at that last meeting (sick, right? Money'll do that to you), and sent them a thank you card a few days later, so I really didn't fancy dropping in on them just to hand over a key. So I kept it. And guess what? The back door of my new house has a generic lock on it, and the key works.