Carl Kelly, 29, from Knebworth, Herts, was even asked to act in a scene with Gwyneth Paltrow. He had wandered onto the set of Iron Man while staying at Caesar's Palace in Las Vegas to watch Ricky Hatton fight last June. When he noticed that part of the hotel's casino was roped off, he decided to take a look. A guard asked to see his pass but he bluffed his way past.

Mr Kelly sat down in an empty chair, and soon found himself next to Iron Man star Robert Downey Jr. He confided to his fellow extras that he was an imposter, but they agreed to keep quiet, and after three hours a make up artist began touching up his features and filming began.

He was so close to the action that he is clearly visible, ringed, in promotional photographs being used to publicise the film.And after seven hours of being an extra, the film's director Jon Favreau asked him to act with Miss Paltrow.

Mr Kelly said: "He said she would put her hand on my shoulder and I was to guide her past the table. Some 38 takes later, I think they were getting pretty fed up with me, but that's what happens when you let an untrained nobody into your film."

After spending the day filming, Mr Kelly, missed his plane home and had to pay for another flight.  He said: "I only found out I was still in the film when I was looking at the website. At least my friends now believe me."

I understand that's how Keanu Reeves got started...

Not every attempt was as successful.

The original was here.