Ah, he must take after his mother? ;)

I was told once that the drinking age on an aircraft relates to the country the aircraft is registered in, but don't know if its enforceable or not

Outside of the Excited States of America...no issue.
I was drinking on board by myself at 16 and 17 on Canadian and International airlines.
Nobody even asked.

Last flight with family, daughter aged 12 was offered a glass of PDB champagne, daughter thought it was a joke, said yes and got a glass - Which i enjoyed.

Every cloud etc.

The next time I’m surrounded by little darlings, rather than grin and bear it, I’ll ask them to take a champagne PDB and share the wealth. 😁

If I had to guess, I would suspect US airlines don't serve minors (under 21) for insurance policy purposes (especially if their insurance is US based). I really have no idea, but every time I've seen US companies have policies that are more strict than what is legally allowed, it is because of insurance. All about the $$$

I didn't ask. They outright asked us for proof of his age before serving him. He was sat in 6K and us 7J/K and they came back to us and asked "excuse me, is that your son? if so, have you got proof of his age please? We're not allowed to serve under 18s".

I'd never ask myself. I remember trying to play it cool when I was 17, unfortunately I looked about 12 at the time

Unfortunately it's not one of those situations where you can say "I forgot my ID. I'm 18, honest." Not that that ever worked for me.

I remember the days of half a dozen G&Ts on LHR-LBA in 1A UK domestic class. No ID there.

This is what I was told on a VS flight when I was between 18-20. I wasn't allowed the welcome Champagne when on the ground, but the Cabin Crew bought me a glass the moment we were in the air and given that reasoning that when in the air it's the registered country but on the ground it's the physical country.

In the USA, minimum drinking age is a state law issue, which is only influenced by federal law; federal law withholds highway funds paid to the states if they don't set certain drinking age restrictions. There is no federal law regulating a national minimum drinking age. The states each have their own, nuanced take on when it's legal to serve and to whom (with parents, at a meal, not on Sundays, etc). At least one state left it to each individual county within the state. Regulating conduct aboard an interstate/international air carrier is the purview of federal law, which my 5-minute lexis search has determined is silent on the issue of a minimum age. Therefore, I am of the opinion that it is cultural expectations, not "federal reggalashuns," which lead to each individual US air carrier's rules on the service of alcoholic beverages in flight.

Of course, none of this is relevant to the individual flight attendant's choice to serve or not to serve, to enforce or not to enforce, just as not every bartender checks ID.

If you will please pardon the digression, the conjunction with this thread - https://www.flyertalk.com/forum/brit...k-daniels.html - reminds me of what is probably my favourite US alcohol fact: the Jack Daniel Distillery is located in Lynchburg in Moore County, Tennessee - which is a dry county.