I know, I was just curious, obviously if same bank then they could just look it up.
As to op's original problem, I did an online transfer some time ago to one of my accounts, I have couple of accounts with same bank but under different sort codes, anyway I used correct account number but wrong sort code, money ended up in someone else's account. It took me ages to get it back, receiving branch said it was up to customer who got it to give permission to transfer it back but obviously they would not give me customer's details so I had to depend on them to try and contact customer. On top of that it turned out to be a pretty much dormant account, which was good in one way as it hadn't been spent! But it made it hard to contact customer, got it back eventually.