It was Lavelle Smith Jr who choreographed Michael Jackson's world tours. Now he's determined to keep those iconic dance steps alive

"That is so poppy, so Rhythm Nation," he says mellifluously in his deep Southern drawl when the group, called Blok, finish and gaze adoringly at him. "I'm so proud of you guys." Earnest discussion ensues about whether Blok should include the Moonwalk in their routine.

It's a last-minute addition, an attempt to impress Smith Jr who first danced with Jackson in the Smooth Criminal video back in 1987. Smith Jr was 21, fresh from touring with Diana Ross around America's casinos, and about to join Jackson on his Bad, Dangerous and HIStory tours, though he didn't know it would be as his choreographer. Jackson was 29, starting to change colour, and introducing the world to another of his iconic moves, the anti-gravity lean.

But we'll come back to that. For now Smith Jr is praising Blok's performance in the way that only American choreographers can. "Y'all can Moonwalk?" he marvels. "That's dope!" Then the man behind some of Jackson's best-known moves, who has worked with the Rolling Stones, Janet Jackson, TLC, En Vogue, and is responsible for getting Beyonc's booty to jiggle like an earthquake in hotpants in Crazy In Love, limbers up and shows us how it's done.

Pushing his heels into the ground, exaggerating his hip and shoulder movements, swaying his buttocks and pouting ever so slightly, he propels himself backwards into the most smooth and stately Moonwalk I've seen since the 1980s. "Michael always said you gotta get the groove, really travel, use your body," says the bald, middle-aged choreographer as he motors around the studio anti-clockwise, looking as serene as a duck on a pond. "Don't sell your moves short."

Next, he watches Blok do the lean, first seen in Smooth Criminal when Jackson and the dancers used wires, and later live in concert where he wore the special shoes he patented to "defy gravity". Blok don't have such props, but they're determined to lean further. "Take a chance," says Smith Jr, as though he's talking about a self-help therapy. "As Michael says, don't let the music control you. You control the music."

Only later, when Smith Jr and I sit down during his lunch break (though he smokes rather than eats) do I realise that he often refers to Jackson in the present tense. Even he points it out. "I still can't believe it," he says of Jackson's death in June of a heart attack. "I still have moments when I say 'is' instead of 'was'. I'll probably continue to do that for a long time. Believe me, I know he is no longer with us. But it takes a while. What we can do, all the people who know him and love him and worked with him and idolised him, is keep dancing."

You couldn't make Smith Jr up. He has that earnest, cheesy, slightly glazed-over look that people often possess when they talk about being close to Jackson. There is a lot of soft-spoken talk of God, love, special gifts, and "our time on earth". But he is also genuine, sweet – almost childishly so – and a true professional. It's clear that Smith Jr is adored by everyone. "No airs and graces," one dancer says when I ask what he makes of the choreographer. "A legend," whispers another.

Smith Jr is from Louisville, Kentucky, "which borders Michael's state, Indiana," he tells me. He's in London to rehearse with the semi-finalists on the BBC3 show, Move Like Michael Jackson. The series, a nationwide search to find British dancers inspired by Jackson, started last Monday and the live final is tomorrow, when the last four acts will battle it out to win a spot performing at the official Michael Jackson Memorial Event at the O2 Arena next June.

Smith Jr choregraphed a brand-new routine to Beat It, featuring five classic moves (the Moonwalk, lean, toe pop, leg kick and crotch grab), Jermaine Jackson, Jamelia and top casting director Mark Summers are judging, and the acts have choreographed their own dances to Jackson songs. Upstairs we watch a more edgy group who blow Smith Jr away as they bodypop and thrust their pelvises to Scream. Smith Jr won an MTV award for his choreography to the video of the Michael and Janet Jackson duet and he's clearly taken with their routine. "I love it, love it," he says. "Those kick steps from the Bad tour, the disco stuff from Don't Stop Till You Get Enough, the neck move, the roll, the crotch stuff ... it's all there."

The last time Smith Jr saw Jackson was on 15 May, a month before he died. "He was great," he says. "It was always amazing to work with Michael. Last year in Vegas I spent five months (with him] developing ideas and moves for the O2 dates." Now, Smith Jr is teaching similar moves to a bunch of British teenagers instead, for the Memorial Event. "I don't expect anything to replace him," he says. "I just want to deal with it. I know time is a great healer. It'll happen, but it's still very fresh. This programme is constantly reminding me. It's an honour to be here but I didn't realise it would be such a big reminder of him not being around. Michael would get a real kick out of this. A real kick."

Were there moments when he was concerned about Jackson's mental and physical health? I mention the superstar's reported addiction to prescription drugs and Smith Jr gets upset. "I didn't see that and if I had I definitely would have said something," he says. "There is just no way I would have let that happen. And anybody who knew and didn't say something should be ashamed. Because there is no way that people didn't know. No way. I can be as naive as I want, and sometimes I can be, but I just can't believe that no-one knew."

Smith Jr was seven when he first saw The Jacksons performing live in his home town of Louisville. Immediately, he knew he wanted to dance. "All the kids came, Janet and La Toya and Randy," he says. "I remember wanting to wear their clothes and have an afro that big. My mum said absolutely not, no way. But she did compromise and get me a suede fringed vest." Smith Jr trained in ballet, then moved to Chicago when he was 17 to pursue jazz. His mother, a nurse, and step-father, who worked in a post office, gave him a year to find success or come home. Three weeks later Smith Jr was the youngest soloist in a jazz company.

By the time he was 19 he had been snapped up by Diana Ross. "I was so young I couldn't even get into the casinos," he recalls. "I only got to go when Diana took me. We did two shows a night for nearly a year." Shortly after, Smith Jr moved to Los Angeles and went to an audition for a Michael Jackson video. It turned out to be Smooth Criminal. "The audition went on for ten days," he recalls. "It was amazing just to see him work. He was so professional. For one week we shot a single scene."

Joining Jackson's entourage as a dancer on the Bad tour, Smith Jr was dropped in it one day when Jackson asked him how he would dance to a particular beat. "I did some sharp military moves, which Michael called slicing meat, and he said, 'That's it'. Afterwards, he kept asking me and then said he had a big number at the American Music Awards and would I do it? It was Dangerous." He went on to choreograph Jackson's world tours, and to date has won an incredible five MTV awards for choreography, a Bob Fosse Award, an Emmy, and is one of the youngest inductees into the Millers Gallery of Greats.

He also choreographed the video for The Way You Make Me Feel, in which Jackson woos a woman essentially with the power and thrust of his crotch. So, how did this legendary move, imitated by everyone from Madonna to Eminem, come about? "It was just a pants issue," shrugs Smith Jr. "Sometimes men's crotches aren't quite right, y'know?" I nod sympathetically. "So you hike it up and then go. It really was as pedestrian as that. Out of necessity. And you know when we slide and open our legs in Dangerous? That was us just trying positions that the human body doesn't naturally do. We always try to live in those positions." There's that present tense again.

Jackson was a formidable perfectionist. He would call Smith Jr in the middle of the night and tell him to come to Neverland and work on some steps. He would make him go over a single step dozens of times. They would rehearse for 20 hours without a break. "It made me a workaholic," says Smith Jr, who admits he is married to his work. He has no family of his own, and a few years ago left LA to return home to Louisville when his mother got breast cancer. He now lives with her in an enormous house with a pool, that he bought for her. "I won't settle for mediocre when it could be amazing. I want to blow the roof off when I work. Good is not enough for me," he goes on. Martin Scorsese once described seeing Jackson dance as "like watching quicksilver in motion". For Smith Jr, it was all about his ability to move to every beat of the music. "Michael taught me to really let the music speak. As choreographers we're so anxious to get up we forget to listen. Michael is like a Bob Fosse to me. He's like Nijinsky or Baryshnikov. There are no other geniuses in pop like him."

He describes Janet Jackson and Beyonc as his little sisters. What about Jackson? "A brother, for sure," he says. "I never look at him as any age because, you know, he always looked fantastic." Really? It's hard to believe that Smith Jr wasn't shocked by the transformation taking place in front of his eyes over two decades but he maintains he wasn't. "People would say to me don't you think his face looked weird? But you know it never occurred to me. I was never looking at that and I was never looking for that. I was looking at an artist. You don't look at your friend of 23 years like that."

Smith Jr starts telling me about some of things they used to do together and the stories are as strange and intriguing as everything we hear about Jackson. "We used to sneak out in New York, dress up, and go and see shows," he remembers. "It was really funny. We took his kids too and I remember picking one of them up and running back to the van. And I enjoyed Neverland," he sighs. "You never wanted to leave that place. Everything was 24-hour. You wanted a movie at midnight? You just called and headed over to the theatre. He would make you feel so at home. There was beautiful music playing everywhere, fountains, a lake, horses. And we rode jetskis. I'd race with Michael but man, he could ride a jetski."

What Smith Jr misses most is the talking. "Just sitting and eating sushi," he recalls, getting a bit misty-eyed. "We used to talk about our dads a lot, how much we loved our mums, girls. I'll miss that. We had similar upbringings, and we don't judge people." His tenses are getting scrambled again but Smith Jr presses on.

His lunch break is up. There are more crotches to be grabbed and leans to take a chance on and now Jackson is gone it falls to his broad shoulders. "Michael was really good at talking about death," he says. "He didn't fear it at all. He gave me insights on how to deal with grief. I don't know any other artist I could feel this way about. I love Beyonc completely and she really is that sweet and talented. But, you know, it's not like me and Michael."

The final of Move Like Michael Jackson is on BBC3, tomorrow, at 9pm

This article was first published in The Scotsman on December 19