I did try to drink a 75cl bottle of Jack Daniels during the last LEL. There was a logic behind turning AUKs flagship event into a bizarre drinking game.
To be able to drink a whole bottle, I'd have to be well hydrated and in good shape. Also, riding at full value pace would allow more time. It works out at a bottle of whiskey over the course of 5 days. I could take very small sips during the day and at night, use it as a nightcap, which is how I drank the bulk of it.
I wasn't going to get drunk or jeopardise my ride, so I wasn't going to drink and be damned and I only drank it if I wanted to. I wasn't going to force myself. I only managed half the bottle, so an unsuccessful challenge.
I don't drink very much as it is (4 units a week is a heavy drinking week for me, most weeks I have none) so although I have rarely drunk alcohol on AUK events, I never drink more than a pint of beer at a time unless I'm about to go to sleep because I'm not used to alcohol.
I tend to go for a bitter shandy and it has worked very well on hot days and I think that it makes a good recovery drink for fluid replacement and giving the blood sugar a little boost.
I think that bitter was originally a refreshment drink for manual workers centuries ago and have heard that it's a good isotonic drink. I've also heard of 24hr TTers putting beer in their bottles several decades ago. AUK patron, David Duffield drank brandy on his end to end tricycle record ride and that, apparently, wasn't unusual.
The trouble is that, relatively very recently, the alcohol content of beer has more or less doubled, which makes it a bit too strong for a lot of people.
I certainly remember feeling MUCH better after drinking a bottle of beer after completing the 3 Coasts 600 and Good Companions 200 double in 2007 and also after having 2 bottles of beer before I went to sleep at the Betwys Coed control on the MC1K last week.
The large beer I had at around 10am while on my last PBP most definitely slowed me down, but I had time in hand and was only riding for fun and I did enjoy it.