We all have our theories and can't ever prove what happened that night, but these are my thoughts:
a. I remember Barrymore being on Big Brother and his crying in the diary room was harrowing, to the extent that I thought he looked like a man who knew he was a monster and could hardly live with it. Not just a man who has lost everything, like he claims, but a man who has seen things worse than the average person can imagine. I can't describe this properly, but he just looked a particular type of fucked-up that I've never seen anyone else look like. After all, most killers are psychopaths and find it easy to have no feelings about what they do. But Barrymore may well not be a clinical psychopath, but rather a horrible person who did something inhuman when he was on cocaine, in which case he knows how much of a monster he is.
b. Barrymore could easily have thrown everyone else under the bus if he wasn't complicit. He seems the type. "Oh no, officer, I went up to bed with a glass of milk and when I woke up this man I didn't know was floating in my pool." The fact that none of the people at the gathering have ever spoken out against each other, makes me think they all contributed to Stuart's rape and death. None of them can say what Barrymore did, because then he could say what they did.
c. I'm too young to remember him being Mr Saturday Night, but he seemed like such a prat. He's just wearing a suit and running around the stage, what's funny about that?
d. I completely hate it when famous men get applauded for coming out as gay, when they've had a wife for years. It's ruining her entire life, but the man gets praise for it. I could have cried for her when they showed her sitting in the audience. What an awful selfish person he must be. Probably selfish enough to not care about anyone's life who he ruined?
e. So yeah, this is where it gets upsetting, feel free to stop reading here... the fact that the pool thermometer and the doorknob went missing, suggest that they were used to inflict Stuart's injuries. The Channel 4 doc has an expert saying that the square top of the pool thermometer matches his wounds.
f. Barrymore was heard my the taxi driver saying, "I need a good duck." This was clearly a case of Barrymore picking up a young man in a nightclub to take home for sex, probably a threesome since his boyfriend was there, and maybe he was planning group sex with all of them. They were on cocaine and whether or not Stuart began by consenting to sex, in the end it became a brutal gang rape, and they were assaulting him with any object they could find. Maybe Barrymore and his friends thought they were the tit and felt entitled to pick up an "ordinary" guy and use him however they wanted. Maybe it was when the drink and cocaine started wearing off that they began to realise what they had done. Maybe they were stupid enough to think that if they threw Stuart in the water, it would look like he drowned.
Either way, I don't believe for a moment that Barrymore was not directly involved.