£10 - Cost of Human Nature

I found a £10 note today. Yes that one in the picture.  Looks like any other £10 note. Thing about this one was that I found it sitting on its own in a cash machine.  I was passing by and heard the machine beeping and saw the £10 waiting for its owner.
I took the money and went into the bank and gave it to the cashier behind the desk.  Hopefully the owner will come back to claim it and it will strengthen their faith in human nature.
I know I would hope that if I left money in the cash machine that someone would hand it in.

What would you do?