Jamie Bell and Scots actor Gary Lewis, once little Billy Elliot and his dad, were now playing fellow detectives in the forthcoming adaption of Irvine Welsh's Filth. On seeing the photograph, Lewis could not hide his amazement. "You're taller than me!" he shouted in true fatherly fashion.
Bell has indeed taken a stretch from playing the miner's son with dreams of becoming a ballet dancer. Since hoofing his way across the floor with Julie Walters to T-Rex's We Love To Boogie, he has jetted across the rooftops of Edinburgh (Hallam Foe) and deftly executed a three beat shuffle through a Peter Jackson (King Kong), a Clint Eastwood (Flags Of Our Fathers), and a Spielberg (The Adventures Of Tintin). No wonder "tap dancer" is still part of his Twitter profile. That, and being a new dad to a baby boy.
With his Billy Elliot background his appearance in Filth might be as jarring to some as watching Fred Astaire take a wrong turn into Mean Streets. But Bell steps seamlessly into his role as the willing apprentice to detective Bruce Robertson (James McAvoy), a man on his 19th nervous breakdown and counting. Bell, 27, wondered if he had the necessary when he first tried to read Welsh's Edinburgh-set novel.
"I picked it up and started reading it and was kind of like ... disgusted. It made me feel uncomfortable, so I put it down." He then read writer-director Jon Baird's "brilliant" adaptation and signed on. Bruce Robertson, Bell reckons, is about to go in the same chapter as Patrick Bateman of American Psycho as one of the great book to movie anti-heroes.
Playing detective Ray Lennox requires Bell to dust down the Edinburgh accent he used in Hallam Foe. The Scots accent is one of the hardest to sell to native ears, but the canny Bell, born in Billingham, north east England, has it nailed. He puts it down to his ear for music.
"There is so much music in the accent. If you listen to it enough you just get into those rhythms and melodies," he says down the line from Los Angeles. It's a city he feels comfortable in, keeping in touch with his family in England by text, email or Skype and visiting whenever he is back in the UK. "I don't think this is going to be home forever, but right now it's working."
When making Filth it helped with the accent to be surrounded by Scottish actors and crew, and a director who hails from Aberdeen.
"Jon was on my case about it every single day. Even our dialogue coach would think it was good and he was like, 'No, there's one word in there that I don't like, or one sound that isn't right.' He was really specific about it but I like that attention to detail."
Lennox is a suit and tie, 9 to 5 kind of chap (what he does after 5 is a different matter). A good office job was something Bell hoped for as a youngster when he was growing up on Teesside. With dad out of the picture before Bell was born, he was brought up by his mother and sister.
"When I was a kid my ambition was to be a journalist, be someone who worked in an office and had those kinds of hours. I was fine with that, I would still be doing something creative, something I was passionate about, something I thought I would be good at." He still finds the idea of routine comforting. "As an actor there is not very much structure so I am sometimes quite envious of that."
Although he won a Bafta for Billy Elliot, he did not see himself making a career out of acting. "It was such a long shot. Even after that movie did well and I had some great opportunities I don't think it's ever a dead cert that 10, 15 years down the line you are still going to be able to do it."
Chosen from 2000 hopefuls, the then 14-year-old had loved the process of making a film, meeting people and travelling. In time, he realised the biggest thrill had been the acting. He had caught the bug.
Filming Filth with Lewis proved to be a very different experience this time. When making Billy their relationship was "difficult, strained," says Bell, because Lewis wanted to dig deep into the part of a deeply conservative, forbidding father who finds it difficult to show his love.
"I appreciate that now because I can see what value it had in the film. Now, I'm grown up and the characters are different, it was just so nice that we could hang out together and talk about old times and hug each other."
Thirteen years on, he remains "humbled" by Billy. "For me it changed everything. I owe everything I have now to that experience and that moment in my life." As he has grown older he also appreciates how much the story of a working class kid trying to gain a place at the Royal Ballet School means to others.
"You would be hard pushed to find someone who didn't want that kid to win. I have never met anyone who was thinking, 'Well actually the whole time I was thinking he shouldn't have got in'. It appeals to the human condition, he says. "There is no trickery involved in Billy. It just has so much heart."
If nothing else, seeing Bell in Filth should prepare audiences for one of his next films. Besides appearing in Bong Joon-Ho's hotly anticipated science fiction film Snowpiercer, he will be seen in Nymphomaniac, the new drama from cinema's leading agent provocateur Lars von Trier. Bell describes the picture, starring Charlotte Gainsbourg, as "disturbing and graphic".
Working with von Trier was another notch on Bell's career post. He thrives on directorial variety. "Von Trier's approach is obviously entirely different to someone like Steven Spielberg. If you take all of these different methods, you hope it makes you into a much more versatile actor and you can take on different things and different roles."
His latest fresh out of the box role is as a new father. Bell and his wife, the actress Evan Rachel Wood, star of The Ides Of March, had a baby boy in July. Though they traded tributes on Twitter ("You are my warrior" he told Wood) they have so far managed to keep the child's arrival as relatively private as their wedding. When we spoke in July he was full of the joys and terrors of being an impending first time parent.
"As much as you say you are prepared, and as much as you have got everything in place and done all the classes and read all the books, I think nothing is going to prepare you for the hands-on experience."
He was looking forward to "figuring things out" and getting into a routine. What else would a born dancer do?
Filth opens in Scotland on September 27.