In licensed establishments, 16 is legal with a meal and then it is beer, wine or cider. [Tsaria, I do not know about Scotland]. In private, surprisingly, it is legal to give kids the stuff at 5. So, Being "sophisticates" of a certain class, those girls have been around alcohol for some time. I imagine even the Queen started drinking wine with meals at an early age.
My comment about 1950 is just an observation that kids are exposed to a lot more now than they were then. And it is a bit too late to shield them from "sleazy" elements now. They were not raised in a convent, after all. Perhaps she is trying to teach them how to deal with them? I have seen better mothers do a worse job of that.
I am aware that there is a most serious binge drinking problem in the UK, especially amongst young women and girls. I do not take the subject lightly. In England, it was like pulling teeth to get the smoking ban, it will be more difficult to raise the drinking age, in my opinion.