It’s a truism, of course, but for the supporters of other clubs it is a fact that perhaps bears to be repeated. There is an entire generation of Manchester United supporters that have never known any other manager. Having been in charge at Old Trafford for twenty-six and a half years, Alex Ferguson has come to define this particular football club and it should come as no great surprise to see that there is a feeling akin to mourning amongst their support today. Coupled with the success that he brought the club – and it doesn’t seem unreasonable to suggest that, in the “hire ’em and fire ’em'” culture of the modern game, his is a record that will never be surpassed – it would hardly be surprising to find that many supporters of Manchester United feel as if they are staring into a void of sorts this morning.

The timing of the decision, it has to be said, was something of a surprise, not least because it might have been assumed that a retirement of this magnitude might have been telegraphed. There are several reasons as to why we might have expected this to happen – to allow supporters of the club to get used to the idea that things were going to change in a radical way, because the quest for a replacement is going to be a difficult to one to carry out in private, or because to introduce a change of this importance which has been anticipated for many years might have needed a clear strategy – and it might also have been expected that Ferguson would want one more go at winning the Champions League that one more time. Having said that, though, this weekend’s match against Swansea City is likely now to be an emotional affair for those lucky enough to have secured tickets for it, a combination of celebration at lifting the Premier League trophy for the twentieth time, sadness at the passing of an era and nerviness at what the future might hold.

In terms of how Manchester United might replace Ferguson, there is a warning from history of which the club’s supporters – even those young enough to only be able to remember his time in charge of the club – will be all too aware of. The retirement of Sir Matt Busby from the club in 1969 cast a shadow over his successors that some have argued was too great a shadow for his successors, first Wilf McGuinness and then Frank O’Farrell, to be able to cope with, and the club’s subsequent decline took many years to correct. Of course, football has changed considerably since those days, and in the modern environment it may be more appropriate to have such an influential figure sitting at directorial level, continuing to offer the degree of continuity that continues to elude all other clubs and has been one of Manchester United’s greatest strengths in recent years.

Inevitably, thoughts subsequently turn to who might replace him as the manager of the club and the early betting on the subject has been haywire, with Jose Mourinho – has a solar system sized ego, has won the Champions League at several different clubs – and David Moyes – is Scottish, has been at the same club for some time performing admirably under tight financial constraints – currently leading the betting, whilst others may now be looking in the direction of the league du jour, the Bundesliga at somebody like Borussia Dortmund’s Jurgen Klopp as being a satisfactory replacement, but in truth each of these appointments may come with their own flaws. Mourinho’s ego may prove divisive and his record, although obviously impressive, hasn’t been unilaterally successful, as may be evinced by Real Madrid’s performance in both La Liga and the Champions League this season have demonstrated. Moyes has little experience of the Champions League and has failed to bring a trophy to Goodison Park. Klopp may be the flavour of the month, but his team has been a distant dot in Bayern Munich’s rear view mirror this season. Perhaps, though, any replacement is going to pall in comparison with his predecessor.

Ultimately, the thorny issue over who is to replace Ferguson is one that has been, as it were, a known unknowable for some time. The outgoing manager has filled a unique space in the firmament of English football in terms of longevity, constant modernisation, success and maintaining a position of authority at a time when the authority of the football manager has elsewhere been eroded by the increasing power of players and those acting on their behalf and the growth of a culture of instant gratification within the game itself. It is difficult to imagine, for example, that that Ferguson’s replacement would be allowed the time that he was allowed at the start of his career at Old Trafford without a trophy of any flavour. Certainly it is likely, though not impossible, that the days of such a grand empire are over, and this is likely a thought that has crossed the minds of those running the club in recent times. How do you replace the irreplaceable? Well, probably not by trying to emulate it in a culture that is not conducive to anything apart from a constant stream of success.

Manchester United will, of course, be fine. Much as rivals might like to see this chink in the armour as a window of opportunity, the likelihood is that a team that has cantered to the Premier League title this season is unlikely to suddenly sink like a stone to any sort of obscurity. The club has, regardless of its debt, a degree of gravitational pull that its rivals can only dream of, and the relative stratification of the Premier League according to the rules of the free market means that any degree of ‘failure’ at the club in either the near or distant future will be strictly relative in nature, and supporters of the club can at least consider that it has had several years to prepare for this inevitability, even if it has seldom passed much public comment on the matter. Still, though, Old Trafford will not quite be the same again, and the cheering of Manchester United’s rivals at his departure up the stairs in the direction of the boardroom might just turn out to be the most apt tribute to Sir Alex Ferguson’s many years at the club that anyone can come up with. In the most literal sense possible, we will not see his like again.

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