I had the reverse recerntly on taking off from the USA coming back to the UK. Champers in hand (glass not plastic) for takeoff. Like you I want expecting it to be whipped away but no. I did however personally take away the empty glass of OJ that my son had and looked after that.

As you say crews seem to vary. Which is nice when it benefits you, but is also one of my bugbears about BA - inconsistency!