I'd only add to to KARFA's reply, that from discussing this (in a socially distant way of course) with BA crew, some cabin crew are getting fed up with people who seemingly take a very long time to consume their food and / or drink, when most passengers are very conscientious in this area. And other passengers complain about it too. I think the word from the top is that cabin crew won't get into trouble if they take a strong line on the issue, so if there is a judgement call that goes toward zealousness, then that would be better than falling on the side of pragmatism. In this scenario I'd say "oops sorry" and take the Chris Wallace advice, it is not worth escalating, I feel.

BA have said they are following government guidelines. The relevant statutory instruments (of which there are now quite a few) all have this line in it, allowing this dispensation for those otherwise required to wear face masks:
"where it is reasonably necessary for P to eat or drink, P removes their face covering to eat or drink"
and that's it.