Cheques must work differently over there. Here you get a guarantee card (usually your Maestro/cash machine card) which states the amount the bank will cover you for - retailers can then take payment up to this amount without risk of losses. If you have £20 in your account and write a cheque for £50, provided the cheque is properly endorsed with your card number and details, then the amount is credited to the retailer by your bank. This results in an unauthorised overdraft and ensuing charges.

Or are you using "checking account" as a loose term? I always assumed it meant an account one could write cheques from?