Are ASDA taking the piss or what?

I fully support ASDA in their efforts to thwart underage drinkers. I applaud their challenge 21 policy, whereby anyone under 21, or who appears to be under 21, has to provide proof of their identity and age. And I know that I've been working out more recently and eating more healthily. But because I'm a real man in the Gene Hunt mould I refuse to moisturise, and rarely use "grooming products." A splash of aftershave and a smear of Brylcream is all I've ever needed, and to be honest, with a number 2 crewcut the Brylcream is only necessary because my hair goes very dry and fluffy otherwise, giving me the appearance of a velcro tennis ball. I do not subscribe to the Cliff Richard Fountain of Youth by abstaining from lifes pleaures, and I'd be the first to agree that I have the perfect face for Radio.
So, how I wonder did the checkout operator conclude that I was under 21? I'm 42 for Christ (or God(s) of your choice) sake. I can pass the requirement twice over. Talk about should have gone to specsavers!
I haven't been asked for ID in over twenty years. I don't really carry ID. I mean I had my police warrant card with me, but that isn't acceptable because it doesn't have your date of birth on it. You have to be 18 1/2 to join the force, but that doesn't prove you can buy a bottle of wine. Rummaging through my wallet I had all sorts of things that give away my age - a Library ticket, Institute of Advanced Motorists membership card and Caravan Club member card - but none show my date of birth. It was only when my son, 8 year old Thomas, asked "what's the problem Dad?" that the operator relented. Obviously she'd done a little mental arithmatic and figured that I must be at least 24 to have an 8 year old son in tow.
So here's a top tip for all you council house chavs out there - take your kid brother shopping with you when you buy your Stella. - hang on, no scratch that, you probably DO have an eight year old son but are still under age to buy alcohol right?