Can you guess how old they are?

(From Off Licence News)

A man dressed in a dark suit strolls into your shop. He's clean shaven and sports a yellow tie and ironed shirt. Looking at his face, you can tell he's fairly young - no more than 25. He might be popping in after work to pick up a bottle of wine to have with dinner, or to buy a four-pack of beer to sling in the fridge when he gets home.

Is there something about his behaviour that has caught your attention? Maybe he's overconfident, eager to make eye contact and engage in conversation? Or perhaps he's starting to blush as he walks up to the counter and is quick to hand over the money.

Any of these actions could signal that this customer is uneasy, and you might scrutinise him more closely. But with a growing queue of customers to serve, how carefully do you study his behaviour? Is a tall frame and smart suit enough to convince you that this man is over-21? As the line-up of customers on the right shows, appearances can be misleading. You might have served the suited man pictured opposite, but questioned the baby-faced blonde guy in jeans and trainers. In fact customer C is only 16 years old, while D is 20. And when you find out that A is 19, B is 14 and E is 15, it becomes blatantly apparent how hard it is to correctly guess a person's age just by looking at them.

Seven stores duped The difficulty with identifying teenage law-breakers was recognised in a recent landmark case which saw magistrates refuse to convict a Dorset retailer after seven stores were duped by a 16-year-old test purchase volunteer.

Graham Northeast, owner of Bonafide Wines, escaped conviction because magistrates decided the teenager he had sold a bottle of Budweiser to in a test purchase sting was made to look over 18. The case goes some way to showing just how flawed test purchasing can be.

"Even the magistrate had to agree the photo offered by Trading Standards did not portray the girl as she looked on my CCTV," Northeast says. "After the Aphotos were taken the girl added a suit jacket, scarf, big adult handbag and purse. My solicitor was not impressed and asked why photos were not taken after test purchases. No credible answer was given by Trading Standards.