You have to grudgingly admire the audacity and dexterity of the sleight-of-hand merchants that try to do you out of tenners. Do 10 shops a day and you've made a hundred quid.

Mohammed Sajid says he always reads this column for news on the latest scams, but here he recalls one of the oldest tricks that people still try on today. His store, M Sajid News, trades in Birmingham and from time to time he'll get a bloke in who hands over a twenty to buy some cigs and after taking the tenner and fiver-plus in change ingeniously manages to conceal the tenner. He'll then claim to have been short changed. It can be readily seen on the till that £18-odd is the change that needed to be paid out so the shopkeeper is unlikely to be mistaken in any way.

"I say, 'well, you'll have to wait until I see the camera'. At this point they usually have a bus to catch and demand a refund for their purchase and they'll often be abusive, especially if there are others in the shop."

Mohammed has a camera on the ceiling above the till and when he views the transaction he can clearly see the till compartments and the tenner and fiver being handed to the customer. But he can't see the concealment. It must be straight up the sleeve.