The poor-sighted star chose not to wear his spectacles to the bash in a bid to look "young and cast-able" after learning Ritchie had invited several movie industry bigwigs, like his A Beautiful Mind director Ron Howard and screenwriter Akiva Goldsman - and he quickly regretted the decision when the host suggested he check out the swimming pool in the basement.

Bettany recalls, "I go into the elevator and I press the basement floor and I go down, the doors open and I'm expecting to hear, like, kids playing in the pool... and it's just pitch black, so I step out into what I think is a corridor but actually it's the black cover of a swimming pool...

"I tried to walk on water but I get wrapped up in the cover and now I'm fighting for my life in pitch black. I'm wearing the watch that my wife bought me for my anniversary and I'm trying to keep it out (of the water) and yet still live.

"I get to the other side and I'm shivering, not with cold, but with the certain knowledge that I have to go back upstairs to a dinner party. I'm drenched.

"I'm looking for a way out of this, as you would. I'm looking for an open window. I'm thinking, 'Maybe I can text my wife and tell her I've left her', and then disappear to Mexico or something and then I see a gleaming row of white toweling robes and towels, so I put on a toweling robe and I sort of put my hair up like I'm Marilyn Monroe... and I go back up to this dinner party... They (guests) pointed and laughed... I step out and I'm literally dripping a puddle on the floor and it was the single worst moment of my life."

Bettany tells U.S. chat show host Conan O'Brien he has nightmares about the dinner party swim, adding, "I still wake up going, 'Oh God no, that was a dream. No it wasn't a dream!'"