It was the Hollywood premiere of the new bone-crunching action movie Parker and co-stars Jason Statham and Jennifer Lopez were engulfed in the usual red-carpet scrum of fans and media.
It was an amazing night with the place full of superstars, says 45-year-old Jason. "But I just couldn't take my eyes off all that jewellery. It was some of the best I have ever seen..."
Old habits die hard and Jason, now one of Hollywood's top action stars, still can't forget the days 20 years ago when he scraped a living selling jewellery from a suitcase on the streets of London's West End.
At Hollywood premieres and parties, people wear the most amazing jewellery and I often wonder who's paid for all that? Jason says.
"I never sold anything with diamonds or anything glamorous. It was pretty cheap necklaces, bracelets and rings. You were always being moved on and you had to watch out for the police.
In those days my ultimate ambition was to have my own legal market stall. I still find it had to take it just what's happened to me."
What has happened is that he's now one of the world's top action stars, lives in style in New York with his partner of three years, 25-year-old top model Rosie Huntington-Whiteley and counts legends like Madonna, Jackie Chan and Sylvester Stallone among his friends.
Parker, already a box-office hit, stars Jason as a criminal anti-hero with Robin Hood-style morals, first played by Mel Gibson in 1995.
As usual, Jason does his own stunts — and one particularly appealed to the man who was once an international diving champion — diving out of a car window at 35mph.
It's just 3-2-1-go and you jump, Jason says. "You don't have time to think about it! OK Parker is not going to win an Oscar but it's great entertainment, Jason says with a grin.
"I know what I'm good at and I stick with it. I'm best in movies that don't pretend to be anything but action films — and this is one of them."
The great thing is I do all my own stunts. Years ago I wanted to be a stuntman and now I get to do a bit of acting and all the stunts I can do — so I've fulfilled the dream I had so long ago.
Jason's parents were in show business — they performed Tom Jones and Frank Sinatra classics in tourist bars in Spain — but Jason had never given acting a second thought until he accidentally met film director Guy Richie who was looking for unknown new talent for his movie Lock, Stock and Two Smoking Barrels.
I suppose you have to put on a performance in the markets if you're going to sell anything but it had never occurred to me to try real acting, he says. "Guy literally picked me off the street and had faith that I had talent."
If it wasn't for him I'd still be dodging around Oxford Street trying to sell jewellery to American tourists!
Jason and ex-footballer Vinnie Jones, two non-actors, were the stars of the block-busting movie. "Vinnie and I had absolutely no experience of learning lines or being in front of a camera," says Jason. "But we seemed to have an instinct for it."
Hollywood thought so too — since then Jason's been in constant demand for movies including The Expendables, The Transporter, Death Racer, Crank and The Bank Job.
Despite his spectacular rise to fame and fortune, Jason has kept his feet firmly on the ground. "I get invited to fantastic parties and get flown around in private jets but many big stars are in fact really nice normal people out of the limelight.
"But most of the people I spend time with I've known since I was a kid and they won't let me put on airs and graces. To them I'm still a market trader who seems to have had a bit of luck!
"A guy I used to work the markets with said the other day that when the movie-star stuff is over and I'm out of work, he'll try to get me a pitch on Hoxton market. Stuff like that make you keep a sense of proportion.
His down-to earth attitude extends to his romantic life, too.
"There are rumours that Rosie would really like to get engaged and is dropping heavy hints about a proposal," says a friend of couple.
But Jason says he won't do that until he feels financially secure. You'd think that with at least $20 million in the bank he wouldn't have any problem with that! (John Graham/Tony James Features)