Just went to the bank with the reciept that had the draft number on it. Can't remember if I said it was lost or just said I wanted to cancel it. Nearly sure I said it was lost.
Anyway, cheers for all the help lads. Ended up dealing in cash which was best for all.
You can't cancel a bank draft, you can sign an indemnity to say that it's been lost stolen etc and have the money refunded, however if the draft turns up you are responsible for it. If he goes to the bank and cancels it it should still be paid.