For two men who have enjoyed the affinity of Felix and Oscar in The Odd Couple, the only surprise is that the combatants survived each other so long.
On one hand, Doug Ellis: "Deadly" he says because of his lack of squeamishness when it comes to dispatching a salmon on fishing expeditions rather than because of his relish for dispatching managers, a 78-year-old correctly-spoken businessman and a senior Football Association figure; the autocratic chairman with an insistence on prudence.
On the other, John Gregory: 47, a man whose ambition is as clearly defined as the lines on his designer suits, hair styled and gelled when in management mode; a confident and charismatic frontman, but a rocker at heart – with his love of Bruce Springsteen – who, given the choice, would watch games "with three days of stubble, sitting with the fans, eating a pie and sipping tea".
What will have astounded no one was that the actual parting of the ways was accompanied by a refusal even to agree reasons. Ellis cited "the pressures that managers endure in modern-day Premier League football". But Gregory responded: "The statement issued by Aston Villa is rubbish. I have no problems with the pressure."
The reality, according to those close to Gregory, is that the frustration of working within the limitations decreed by Ellis finally propelled him to the ultimate act, although their relationship had reached a point where it was terminally unstable anyway. Notably, the former Villa player was affected by Manchester United's purchase of the Uruguayan striker Diego Forlan, a player Gregory wanted for Villa, but was refused the backing to sign.
Gregory, currently on a break in America with his family, has inevitably been linked with second-to-bottom Derby County, who have a vacancy but scarcely offer a position that suggests significant opportunity for success. However, those close to Gregory say that he would certainly consider it. Everton are another club who may covet his talents.
Leaving Villa with the club in seventh place and after two consecutive victories, Gregory's stock is reasonably high, although his teams have not been universally admired for their entertainment value or positivity. There are also, no doubt, current players and certainly former ones, Stan Collymore for one, who would contend that he lacked sensitivity when dealing with his personnel. David Ginola and Paul Merson are among those who have been told by Gregory: "We don't change to suit you; we don't bow to you and change our game. You have to change your ways to accommodate us."
But what of Villa? There are, at a conservative estimate, over 20 contenders, from the anticipated figures like George Graham, David Platt and Alan Curbishley to those one might have considered unlikely, such as Alan McInally. The former Villa player, now a BSkyB pundit, has been reportedly heavily supported with the nation's bookmakers, who are revelling in the uncertainty of the situation.
Former Holland and Barcelona manager Louis van Gaal – it was his name being associated with the club that infuriated Gregory, despite Ellis's denial that "I've never spoken to Louis van Gaal or attempted to make any contact with him" – remains a possibility. The belief is that Ellis and his board, who now include Graham Taylor, will look for a younger man, preferably an ex-Villa player. But with Ellis, you can never quite tell. This, after all, was the man who hired – and pretty soon fired – Dr Jozef Venglos.
Gregory gave an insight into the club and the frustrations in managing it when I interviewed him last season, on the eve of Ugo Ehiogu's departure to Middlesbrough. "Aston Villa is a great club, a fantastic club, but I don't think it will ever be a club without problems," he told me. "I don't think it will ever change. I don't enjoy the summers. They're awful. I've had Ugo banging on the door for the last three, wanting to join a club that's better than us, a club with more ambition, a club that's likely to win more trophies. Obviously, the chairman gets a lot of pressure from the supporters and the media, but this 'lack of ambition' tag is hard to shake off."
He added: "We're not paupers but it's difficult... and we're still expected to win the Premiership. That is hard. It's tough to compete. Because for me it's all about money. Whoever has the most money wins. The richest clubs tend to win every-thing. I just feel we have to compete a bit more in the transfer market. We have to get the best out of what you've got." However, he admitted: "Your signings have to be right, and I've made one or two which haven't come off. I haven't always spent as well as I could have done."
And that encapsulates the last four years at Villa Park: a chairman fearful of over-expenditure on players who may fail to live up to expectation, and a manager desperate to prove himself among the élite rather than the fair to middling of the Premiership. Ellis is in many ways a decent man, but when Gregory once described him as being "stuck in a time warp" there was probably more than an element of truth.
The game has changed significantly since Ellis had his first spell as chairman of the club back in 1962, when he inherited Arthur Cox and then brought in Tommy Docherty. Pride will no doubt dissuade him, but this may be the time for the chairman to review his own position at the head of one of the country's major clubs, and ponder whether the pressures of chairmanship in the modern-day Premier League are not proving too daunting.
Meanwhile, it is unlikely that Gregory will be inactive for long. Indeed, you suspect that his greatest regret will be that his decision was considerably overdue.