http://www.tesco.com/groceries/Product/Details/?id=252405965
0.05% to be precise, so it technically isnt alcohol free - hence the age restrictions. Its a bit like Rizla's and filter tips, they arent Tobacco - but get the same treatment in shops and are age restricted (that and it is obvious...
Company I work for still class it as alcohol and tell us to refuse any sale for it, though I have never had too. Kids would rather not drink, or just have their mates alcohol, than have alcohol free beer.