If you want a more formal, and challenging, approach, send the guy a letter (by recorded delivery) along the lines of the following:
"Dear John Smith,
Your cheque, dated xx/xx/xx, for the sum of �xxx.xx has been returned to me by my bankers, marked 'refer to drawer'.
It is my belief that you may have written this cheque in the full knowledge that there were insufficient funds in your account for the cheque to be honoured by your bankers.
I write to demand immediate payment of this amount, in full. I will only accept payment in cash or by banker's draft. TAKE NOTICE that if payment is not received within 14 days it is my intention to
(i) commence proceeding against you in the County Court, seeking payment of the amount owed to me ; and
(ii) notify Blogshire Police of an apparent contravention, by you, of the provisions of Section 2 of the Fraud Act 2006 (which refers to 'fraud by false representation', for which the maximum penalty is ten years imprisonment.
C. Cuddler"
Chris