So! It turns out that my bank thing is quite interesting and a useful lesson for me.
It seems that I opened a regular savings account 7 years ago and set up a standing order to send £250 a month to it. I then realised that the customer services at that bank was rubbish and closed the account, but the standing order did not get cancelled (oops).
After that time the payment was going over and bouncing back every month for 6 years. It's shown on all my old statements. However recently the account number of my old account was reallocated to a new customer (in February of this year), and he started receiving my payments. Isn't that weird?
It seems he sent three of them back and then started complaining to his bank, who did nothing. It's only now that he's finally complained to my bank.
It makes me realise that my own finances need to be radically simplified so that I can keep track properly. I am thinking now about how to do that.
Yikes!