When I was an underage drinker I was surprised that I wasn't challenged more by the bar staff. Maybe they simply didn't care. But as someone who is now legally classed as an adult I wonder how well a bar full of teenagers would do financially. We were not big spenders. I knew one guy who at 16 used to drink in the same pub as a lot of the teachers. They may even have had beers with him. I wish they could see how he turned out. Hanging out with the kind of guys who leach off kids in a pub isn't a good start in life. As I say, an older guy now, I wonder how we got away with it. I suspect it might have been that to adult most folk under 20 years old look 15 and you can't turn 'em all away. The thing is that teenagers like to be different - though not getting-picked-on different. Anyway they adopt bands and stuff like that as tribal totems. And if you recognise the band name on the Tshirt, or whatever, you can pretty work out how old a person is from their musical taste, or whatever. But a person over-21 and working in bar wouldn't be able to consistently spot the tells.