The old fella in the rumpled suit and Millwall club tie ambled over to the glass doors in The Den's entrance hall, peered outside and muttered a mild expletive.

"There must be hundreds of them out there," he said, his eyes drawn to the swarm of fans that had descended on the stadium on a dank, grey Tuesday morning in the hope of gobbling up a Wembley play-off final ticket. "Who would have thought it?"

The answer, put plainly, is very few. Millwall are a club reborn, the memories of relegation from the Championship, incompetence in the dug-out and chaos in the boardroom banished by a season which has defied the expectations of all but the most blinkered devotee.

On Sunday, Kenny Jackett's young team will stride out in front of 45,000 of their supporters to tackle League One rivals Scunthorpe United.

A place in the Championship is at stake but this is about more than just promotion.

Pride has been restored and now, at last, the old joke about Millwall FC being the only part of south-east London not to have enjoyed regeneration can be put into cold storage.

By any standards, the transformation has been extraordinary. Millwall may now be swaddled in a feelgood factor but not so long ago they were a by-word for venomous in-fighting and defective leadership, a club left rudderless after the resignation of Theo Paphitis - now the star of BBC TV's Dragons' Den - as chairman in May 2005.

Three chairmen - Jeff Burnige, Peter de Savary and Stewart Till - came and went in a flash as the club struggled to maintain the high standards set under Paphitis and his last manager, Dennis Wise, which included reaching the 2003 Championship play-offs and the 2004 FA Cup Final. However, two seasons after Cardiff, they were relegated to League One.

"It was a seriously unsettling time for everyone," said Heather Rabbatts, who was appointed as the deputy executive chair of Millwall Plc on Till's arrival in May 2006. "Stability is the Holy Grail in football but we had four chairmen in a year. That's just not workable on any level."

Still more seriously, last summer Millwall found themselves targeted by Graham Ferguson Lacey, the notorious property developer and corporate raider, who, having already bought up almost 30 per cent of the club's shares, demanded an Emergency General Meeting to wrest control away from the board and make every decision, from player transfers to buying a new drinks machine for the training ground, subject to shareholder approval.

Rumours swirled of Lacey's long-term intentions and, in particular, the future of The Den as the club's long-term home.

It was only on the eve of the EGM that John Berylson, an American businessman who took over as chairman from Till in October 2007, announced he had become the club's majority stakeholder after converting a £2.3million loan into shares.

Supporters breathed again as Lacey's move was defeated, although the disquiet at seeing the club taken to the brink of more chaos proved much harder to dispel.

"Mr Berylson's investment was a massive moment in the history of Millwall," said Rabbatts, the former chief executive of the London borough of Lambeth. "Without it, we were staring into the abyss. It was a very scary time but we just had to make it work.

"Football is one of those industries where you have to care about people and those who see it as simply an investment opportunity miss out on so much in terms of the passions that surround it.

"There are very few investors who get the chemistry that surrounds football but Mr Berylson does. He's very much a Millwall man now."

Even Millwall supporters, who are notoriously suspicious of those in authority at their beloved club, appear to have taken Berylson to their hearts, while the man himself appears equally smitten by them.

Despite being based across the Atlantic, Berylson has attended more than 20 first-team games this season - he even strode onto the pitch after last week's semi-final at Leeds to salute the travelling fans - and is in regular telephone contact with Rabbatts.

There are also daily phone calls to Jackett, whose seismic impact since being appointed as Willie Donachie's replacement in November 2007 belies his quietly-spoken style and modest managerial CV.

"It has shocked us, in a pleasant way," Rabbatts admitted. "We all felt when he arrived that he had it in him but I don't think anyone was quite anticipating the success we have had.

"We interviewed five or six candidates in the end but Kenny was the stand-out applicant. You can look across managers and it's those people with emotional intelligence and man-management skills who are coveted most. Kenny's proving he has that."

Ultimately, promotion to the Championship - whenever it is achieved - is merely the first step on a longer road for Millwall. Negotiations are ongoing with Lewisham council and the owners of land surrounding The Den to maximise the area's commercial potential, with the fiercely-ambitious Rabbatts suggesting that South Bermondsey could yet undergo the kind of overhaul enjoyed by the previously run-down Drayton Park prior to the impressive construction of Arsenal's Emirates Stadium.

"We make a loss, as most clubs do, but the ambition is certainly there," Rabbatts said. "In three years, I think the aim has to be for us to be a consolidated Championship club. Then we'll look to press on again. That's what all the best clubs should do."