Originally Posted by
cauchy
Only absolute age-based prohibition is against giving alcohol to under 5's in England & Wales (Scotland has no minimum age)...
Also, an aircraft isn't licensed premises, it's outside the remit. Same for a train, but while in motion. This is why, technically, you cannot be served alcohol on the train while it's in a station. It's also why the usual license condition of 'must provide free drinking water' doesn't apply to aircraft and trains.
In the good days of GNER they'd often start serving drinks in the restaurant upon boarding and before the train departed.
When I used to use the Caledonian Sleeper you could order from the lounge car long before the train departed