Most of my travel (95%+) is for work and is mostly longhaul, so I will drink very little at all. I do not believe that my employer would be pleased if I was abusing their spend on J/F travel to get me to my destination in a relaxed, fresh and ready-to-work position by drinking heavily before or during a flight. I recognise others may be different, but if my employer is expecting me to be work-ready on landing, I personally cannot achieve that after more than one or two drinks (maximum). Considering my occupation, alcohol does have a direct impact on my ability to perform. Therefore, I may have a G&T before lunch on a day flight, but on a night flight I typically wont have anything at all - since I want to sleep. My drug of choice on night flights is a 50mg Nytol which gets me to sleep pretty quickly after take-off, particularly on short overnight sectors (e.g. from JFK/PHL to Europe).

For leisure, I will have a few drinks but maybe 4 or 5 maximum, since I don't want to end up blind drunk but enough on a long 12 hour flight to relax. Again, if sleep is on offer, that would be my go-to as opposed to staying awake and drinking.

I did see a gentleman once completely wasted boarding a flight from LHR to JFK in F, then the CC serving him more which I did think was unacceptable, but hey, who am I to judge I do find it a little bit odd that those who say they drink a lot before or during a flight because it is "free" - it is a lack of self-control on their part drinking on someone else's dime, since they would not likely do that on their own dime.

Finally, I observe drinking culture being much heavier on BA that other carriers I use (CX, QR, LX etc). Being British myself, I know it is an unfortunate part of our culture.