There were many dejected figures at Stamford Bridge on Saturday, but for all the glum looks on the faces of Chelsea’s young millionaires as they contemplated the death of their Barclays Premiership title challenge, there was no one more crestfallen than the man in the visiting team’s dressing-room, who sat on his own while his Bolton Wanderers players exchanged high-fives.

This was the moment when it dawned on the Bolton players that the rumours might be true, that Sam Allardyce might be about to leave. By the time the team bus departed half an hour later, with the manager nowhere to be seen, they had begun to fear the worst. They began to speculate that he might announce his departure before the final match of the season, at home to Aston Villa on May 13, but instead the announcement came yesterday afternoon that, after eight years in charge of his home-town club, he was leaving immediately. Kevin Nolan, the Bolton captain, declared himself “shocked and completely devastated”.

Devastated? That is understandable, given the amazing transformation of the club since Allardyce’s arrival from Notts County in October 1999. But shocked? Bolton’s players have had plenty of time to get used to the idea of life without their inspirational manager. The first question that arose upon hearing yesterday’s announcement was not where he might end up — with Manchester City or Newcastle United the most likely destination — but why it had happened now, rather than 12 months ago, when it was first mooted.

It is a year and four days since Allardyce, standing at the bar in a Barcelona hotel, learnt from a couple of journalists that he had missed out on what he had called his “once-in-a-lifetime” opportunity to be the man in charge of the England team, with the FA flying to Lisbon that night to offer the job to Luiz Felipe Scolari before Steve McClaren was finally appointed.

Allardyce and Martin O’Neill, a fellow candidate, let out a nervous laugh and had another drink, but in Allardyce’s case at least, rejection was hard to swallow. “I thought this was the perfect time for me,” he said a couple of days later and, as in the weeks that followed, there were whispers about his future, that he was ready to turn his back on Bolton and take a sabbatical to prepare for a new challenge.

As it transpired, he was persuaded to throw himself into one more season with Bolton and he leaves them on course to finish fifth in the Premiership, which would be the highest league finish in the club’s history. He led them to more great victories, over Arsenal and Liverpool, but somehow things were not quite the same.

He spoke at the start of the season about the difficulties in “remotivating yourself and starting again when you’ve come so close”. And that was before the BBC’s Panorama programme in September that made serious allegations about his son Craig’s involvement with Bolton as an agent and posed new challenges to Allardyce, challenges that had nothing to do with football.

Panorama, too, took its toll on Allardyce, who revealed that the associated stress had caused him numerous sleepless nights and led him to start smoking again, four years after he had given up, supposedly for good. More trivially, there was also a noticeable change in his dealings with the media as the Premiership’s most quotable manager became more reticent and followed Sir Alex Ferguson’s lead in boycotting the BBC as a result of the Panorama documentary.

The decision to leave Bolton is one that Allardyce has reached after a great deal of agonising with his family, but it is one that, it transpires, has been weeks and possibly months in the planning. Claiming fourth place ahead of Arsenal and reaching the Champions League might have changed his mind, but as the season entered its final weeks, he concluded that he had taken the club as far as he could. His wish had been to stay until the end of the season, but Phil Gartside, the chairman, having been shocked to learn of Allardyce’s intentions on Friday, decided that it would be better to make an immediate break.

Allardyce must decide what the next challenge is to be. A vacancy at Newcastle would hold a certain appeal, but the strongest link is to City, even if his greatest hope of landing that job, which is occupied at present by Stuart Pearce, appears to rest with a takeover bid by Ray Ranson, which continues to be looked upon unfavourably by the Manchester club.

THE REIGN OF BIG SAM

Sam Allardyce’s appointment as Bolton Wanderers manager in 1999 barely registered on the football landscape, but his arrival heralded a magnificent new era at the club

October 1999: Appointed manager after previous managerial spells at Limerick, Blackpool and Notts County.

May 2000: In his first season, guides Bolton to the first division play-offs, where they lose to Ipswich Town, and an FA Cup semi-final.

2001: Takes Bolton back to Premiership after three-year absence with 3-0 win over Preston North End in play-offs final.

2004: After his nous in transfer market brings in Youri Djorkaeff, the France World Cup winner, and Jay-Jay Okocha, the Nigeria star, in 2002, Allardyce sees signings steer Bolton to eighth-place finish in Premiership. But they are beaten by Middlesbrough in Carling Cup final.

2005: Bolton finish sixth to claim Uefa Cup berth for first time in history.

2006: Allardyce’s troops reach the knockout stages of Uefa Cup, where they are beaten by Marseilles, and again claim an eighth-place finish in Premiership.

2006: Allardyce cements position as one of the country’s most highly rated managers as he narrowly loses out on role of England head coach to Steve McClaren.