Sam Allardyce has an evolutionary theory for his particular species. "As a manager," he says, "you accept that you need a double skin: a rhino's skin and an elephant's skin to survive in the job."
West Ham United's manager has had the best part of 20 years to toughen up his hide yet that did not stop him from feeling sore and instructing his lawyers earlier in the week when the video footage of Steve Kean slating him appeared on YouTube. Allardyce's revenge stands to be meted out by more than the libel silks. The script calls for him to lead West Ham to victory over Blackpool in the Championship play-off final at Wembley and so swap places with Kean's relegated Blackburn in the Premier League.
They used to be his Blackburn, of course, only that changed when the newly installed owners Venky's fired him in December 2010 and promoted Kean in his stead from the coaching staff. Allardyce has an axe to grind with Venky's.
Saturday afternoon's Wembley showpiece has additional intrigue.
Allardyce's first permanent managerial post in English football came with Blackpool and it ended badly when, after the 1996 division two play-off semi-final defeat to Bradford, the club's owner at the time, Owen Oyston, who was imprisoned, sacked him from a prison cell. Allardyce's team had won the first leg 2-0 but contrived to lose the second, at home, 3-0.
"It was devastating because I thought I might have been lost to football, I thought I might not get back into the game," Allardyce says. "I was only two years managing in this country. Have you built enough of a reputation for someone else to give you a go? It took eight months before Derek Pavis gave me the chance to manage Notts County and my career grew again. Many managers in that position never work again as a manager."
Oyston's son, Karl, is now Blackpool's chairman. "I've seen Owen a couple of times since," Allardyce says. "He's looking well for his age, he's still wearing that hat. They said it wasn't Owen's decision, it was a board decision. It was a huge blow to me at the time but it's long gone, water under the bridge."
It has been a gruelling first season at Upton Park for Allardyce, during which he has felt the wrath of the club's fans for his playing style and erratic home results. One stick to beat him with has been his non-use of Ravel Morrison, the mercurially gifted but difficult 19-year-old midfielder, who arrived in January from Manchester United. Some United players speak in awed tones about his talent.
But Allardyce continues to throw punches, he continues to believe that vindication will be his, even if a little wariness undercuts his confidence. "You [the media] will suggest if we don't win that because you haven't gone up in the first year, your job might be on the line," Allardyce says. "I can hear the question now. But I hope I don't hear it after the match."
West Ham began the season as hot favourites for an immediate return to the Premier League, following the trauma of relegation under Avram Grant, and Allardyce did little to dampen the expectation after his appointment last June. "We want to go up automatically," he told the Observer in July. "And if we don't quite achieve that goal, then we are going to be left in the play-offs, at the very least, unless I become the worst manager ever overnight and the players become the worst there has ever been."
Allardyce swings between an acceptance that promotion is the minimum requirement to a grumpiness that the squad's achievement in getting this far has brought no credit. In some respects, it reinforces a theme of Allardyce's managerial career. At Blackburn and even Bolton Wanderers, where he spent eight successful seasons, he did not always get the praise that he deserved.
"People turn round and say 'You're supposed to do this anyway', and that's been something that we've had to live with right from the start because we're a massive club," he says. "It's been difficult in that we've only been doing what everybody's expected us to do."
The nerves will churn inside Allardyce when he leads a team out at Wembley for the first time since 2000, when his Bolton lost on penalties to Aston Villa in the FA Cup semi-final — "Dean Holdsworth missed a sitter [in the] last minute, I still haven't forgiven him," he says, with a smile — while to Allardyce, the occasion is no undercard to Chelsea's Champions League final against Bayern Munich in the evening.
"The bigger game is on Saturday afternoon," he says. "The Champions League final is a glory game. This is about your livelihood and your status. The Champions League is a major tournament but this one is about changing people's lives."
Allardyce is fortified by his experience of high-pressure situations, particularly the battles that he waged to keep Bolton and Blackburn in the Premier League. He takes a fighting fit and in-form squad to face opponents that they have already beaten 4-0 and 4-1 this season. West Ham have sold out their 35,000 ticket allocation; Allardyce predicted that 45,000 Hammers would find their way in. It is make or break. Big Sam can scent the big time.