It is Tuesday afternoon and an hour or so after training Pelly Ruddock Mpanzu, wearing white crocs studded with Super Mario, Superman and Batman charms, walks into the Eric Morecambe Lounge at Kenilworth Road, Luton Town’s creaking but charismatic ground. The room – home to trophy cabinets, photos of comedy nights here and a panoramic mural with a timeline celebrating the club’s storied past – has an orange glow and Mpanzu a beaming smile as he embraces John Still, the manager who brought him to the club a decade ago, when Luton were toiling in non-league.

A teenage Mpanzu initially joined on loan from West Ham, making his debut at Staines Town in the FA Trophy in front of a crowd of 621, before Luton paid £50,000 to make the move permanent. Those who know Mpanzu talk of a laid-back character with a contagious personality and he is calmness personified in the buildup to the Championship playoff final, the most lucrative one-off game in the world. The 29-year-old grew up in Hendon, north London, and could spy Wembley from his back garden. He remembers the iconic arch lighting up in the distance. “I’ve been chilled, I’ve been myself,” he says of the buildup this week. “There is no need to be nervous because we know what we can do on the pitch against Coventry. We’ve gone about our days the same as we have the whole season.”

It is all a long way from playing Sunday League for Belmont United, earning £50 a week after joining Boreham Wood at 16, when the £13 fine for bookings hit hard, and even the times when Luton would train on a field off Ely Road, where dog walkers would complain about low-flying balls. Back then the training ground was portable buildings and one rack of gym equipment had to satisfy an entire squad. How would Mpanzu describe his journey to this point? If Mpanzu were to make it to the Premier League with Luton, he would become the first player to represent the same club in every division from the fifth tier to the top flight. “Yeah, not a lot of people do it … well, I don’t think anybody has done it yet,” he says, breaking into laughter. “So it would be a first!”

The midfielder, a boyhood Arsenal fan, has been central to Luton’s extraordinary rise and is the life and soul of the club. “You hear him before you see him,” says the Luton manager, Rob Edwards. “And you do see him quite often as well … I don’t know if you’ve seen the pictures?” Mpanzu is known for his bold dress sense, be it Hawaiian shirts or bucket hats, and turned up at the end-of-season dinner this month in a purple suit. He previously raised hundreds of pounds when auctioning his flowery blazer in aid of SoLYD, supporters of Luton youth development. Club tracksuits, however, will be the order of the day on Saturday at Wembley. “He is larger than life, he’s exuberant, dynamic … he’s kind of everything the club isn’t,” says Kevin Harper of the Luton Town Supporters’ Trust. “We absolutely love Pelly Ruddock Mpanzu.”

He played once for West Ham, at Burnley in a League Cup win, but joined Luton on loan a month later. Dan Potts, son of the former West Ham defender Steve, also featured at Turf Moor and followed Mpanzu to Luton in 2015. “Did I want to come here? Absolutely not,” Mpanzu says. “I was like: ‘Aaah, this is not what I’m familiar with,’ but sometimes you have to take risks. I have got to thank John for signing me, because look where I am now.”

Mpanzu has substance as well as style. A rocket of an equaliser against Dartford, in his first season at the club, sticks in the memory for Mpanzu, Still and supporters alike. After winning the Conference in 2013-14, Mpanzu lobbed one of Andre Gray’s boots so far it got wedged at the back of the Main Stand and Gray, who would go on to play in the Premier League for Burnley and Watford, continued the celebrations on one foot. “He’s just a brilliant guy whether we’ve won, lost or drawn, it’s hot or cold, it’s a miserable Monday morning, whatever,” Edwards says. “He is the heartbeat of the group because he’s been here for so long. He is so hard-working and he’s just stepped up, stepped up and stepped up. To go up and do one more level would be incredible.”

Two years ago Mpanzu made his debut for DR Congo and a few of the country’s shirts have since been spotted on the terraces. Mpanzu’s raking slide tackle on Sunderland’s Pierre Ekwah deep into second-half stoppage time of their second-leg playoff semi-final victory, to clear the ball into the opposition half from the edge of the Luton 18-yard box embodies his – and the club’s – tenacity. When Mpanzu arrived to sign for Luton with his mum and agent the club were desperate to escape non-league after four testing years.

“When he came he was young and to play in front of the Luton fans is not easy when you’re a senior pro, let alone a young lad coming from a category one academy,” says Ronnie Henry, who captained Luton back into the Football League nine years ago. “The fans are expectant. But they took to him straight away. It has not always been plain sailing for him but he’s been really resilient. When he first joined he was a really bubbly lad. He was always overexcited about everything, but it was infectious and he deserves all the plaudits he gets because he’s an amazing story.”

The players who join Luton invariably ask Mpanzu about those days in non-league. “They ask me: ‘What was it like back then?’ I was like: ‘This place was bonkers, it was mad,’” Mpanzu says. “But everything has gone up a level. I think I’m still the same. Still smiling, still bubbly, still joyful, love the camaraderie, love joking around with people. I’ve obviously grown physically, I’ve become a man and now I’m really enjoying my football. Before it was a bit like: ‘Do I really want to do this?’ Now my football is flowing and I’m enjoying it a lot.”