Can you tell whether a youngster is 16 or 18? If off licence staff get it wrong, they can end up in court. CHRIS TITLEY reports on a new scheme to help shopkeepers defeat underage drinkers.

GRACE Cook didn't drink when she was under age, although some of her classmates at Lowfield School did. Her youthful appearance would have made it impossible for her to buy alcohol anyway. "I don't look old enough even now," the 22-year-old confessed.

It is often difficult to distinguish between an adolescent and an adult. Children are as desperate as they ever were to grow up fast, and some of them are convinced that alcohol is the elixir of age.

That is why youngsters try to buy booze at almost every shop with an off licence, and Tesco Express, in Acomb Wood, York, is no exception. As a customer assistant, it is up to Grace to spot them. Get it wrong and she can face a fine and the sack. Not surprisingly she has become a seasoned spotter of the underage con artist in her year with the store.

"If it's a girl they generally have older clothes and make-up on. They're probably a bit excited, or looking at the floor, all shifty," she said. "They normally have the exact money as well."

Boys are more cocksure, but find it trickier to camouflage their true age. Both sexes' favourite tipples are the same: cheap cider and alcopops.

On an average Saturday shift behind the till, Grace invites around ten young-looking customers to prove they are old enough to buy the booze in their basket. "Most of them will have IDs," she said. "The odd one or two won't."

The number of such age-related challenges has gone up since Tesco rolled out its Think 21 programme to every store in Britain in 2004. Under this scheme, staff asked anyone who looked under 21, as opposed to 18, for ID if they wanted to buy alcohol. If they couldn't prove they were over 18, then no sale.

The principle is a simple one. It is far easier to judge the difference between a 16-year-old and a 21-year-old than that between a 16 and an 18-year-old.

Certainly it helps people such as Grace. "If you ID somebody, you are thinking 'do they look 21?' Because I am quite young, I ask myself whether they are about my age.

"You tell them, 'you have to look 21 rather than 18' and they don't take much offence."

When buying alcohol at another store she was herself asked for identification. "It was really weird. But it has to be done. It's quite a compliment as well."

So successful was the Tesco initiative that it has evolved into something which has spread throughout the trade. Last month the Home Office and retail groups joined together to boost the profile of the scheme, now called Challenge 21.

Everywhere from Sainsbury's to your local Spar now boasts posters and badges drawing attention to the fact that everyone who looks under 21 will need to show ID to buy alcohol.

"We are working to create a culture in which all young people expect to be challenged when they attempt to buy alcohol," said Kevin Hawkins, director general of the British Retail Consortium.

"The first step towards creating this culture is effective communication with the target audience. This new signage, which we intend will be prominently displayed in all off-licensed shops and stores, will get the message across in a much more forceful and effective way."

Acceptable ID includes a passport, or a PASS card - standing for Proof of Age Standards Scheme. There are over one million of these in circulation and although many fake IDs are circulating, the Home Office say that any card carrying the PASS hologram is genuine.

If people are expecting to be challenged, they are less likely to react negatively. Unless, of course, they are trying it on.

"Most people are sensible and just leave if they don't have ID, but I have had a number of situations where people have been abusive when I have asked them for ID," said Grace, of a recent experiences at Tesco Express, Acomb.

"On one occasion a young boy tried to buy alcohol. I asked him for ID, but he did not have any so I refused to sell the alcohol to him.

"He was really rude to me, but then went away.

"I saw him pass the money to a friend who again tried to purchase the alcohol - I asked him for ID, but he too did not have any and was very abusive. I then called the manager for assistance."

Shop workers' union Usdaw is working to reduce the amount of abuse directed at its members. General Secretary John Hannett said: "Staff in all stores that sell alcohol often face problems from youngsters wanting to buy alcohol or other products with age restrictions.

"Usdaw's survey of violence and abuse suffered by shopworkers found that asking for proof of age or refusing a sale because of lack of ID was the most common trigger for threats, verbal abuse and even attacks - with assistants either being punched or kicked in the store, or assaulted by a group who wait until they leave work.

"That is why Usdaw has worked with Tesco to make sure that there is strong support available for all sales staff, so that they cannot be intimidated into making a sale.

"We are also very supportive of Challenge 21 - young people need to know that they must expect to be asked for ID in every store that sells alcohol."

Tesco is keen to ensure all frontline staff know and implement Challenge 21.

"We implement this through staff training with repeated refresher courses - this involves role play situations which help our staff to deal with threatening situations," said a spokeswoman for the supermarket chain.

"Customer information is also available both in the beers, wines and spirits aisles and at checkouts and we have rigorous in-store processes including till prompts."

Challenge 21 should ensure that fewer off licences are caught selling alcohol to under-age customers in one of the regular "stings" carried out by York Trading Standards.

More importantly, the scheme should make it harder for youngsters to get their hands on alcohol.

Alison Tubbs, of York Alcohol Advice Service, said: "I think it's a very good idea. If you are 18 or over you're not going to object."

She says the fact that we are all more aware about the problem of underage drinking does not necessarily mean it is getting worse.

"Young people are a lot more open about their drinking these days. It's better for us that it's out in the open: we can help them and they can address the problem for themselves."

While it is good to see Home Office support for the Challenge 21 scheme, the Government really needs to put its money where its mouth is and fund more support workers, Alison added. "We have only one full time specialist alcohol worker for young people for the whole of York."

Updated: 10:09 Tuesday, January 17, 2006