IT sounds like the name of one of Sherlock Holmes’ cases, but for the recently-departed Roy Keane, the mystery is all too real.

“The curse of being the Manchester United manager in waiting” is an unexplained footballing phenomenon. And on Thursday, it struck again.

A matter of weeks after he was described as Sir Alex Ferguson’s likeliest successor, Keane was leaving his job at the Stadium of Light and throwing his candidature into question.

Interestingly, he is hardly the first person to have suffered such a fate. When it comes to surviving as a manager in the Premier League, the best advice would appear to be to put as much distance between yourself and Old Trafford as possible. Otherwise, you’d better prepare for a grizzly fate.

Bryan Robson was Ferguson’s first successor in waiting – now, he cannot get a job in the whole of the Football League.

His star has waned to the extent that it would be inconceivable for him to be appointed as the manager of his former club, yet once it was expected to be a seamless transition.

Robson was still revered as Captain Fantastic when he moved into management, and the early years of his managerial career suggested he would be every bit as successful in the dug-out.

He led Middlesbrough to the Division One title in his first year, but four years later he was humiliated when Terry Venables was drafted in to work above him.

A disappointing spell at Bradford followed, and while Robson returned to England’s top two divisions to lead West Brom and Sheffield United, his managerial career was anything but stellar.

He returned to Old Trafford in March, just as the soothsayers predicted he would, but currently performs an ambassadorial role that is rather less rarefied than the position of manager. Things, it is safe to say, have not worked out well.

The same could be said of Brian Kidd and Steve McClaren, two of Ferguson’s right-hand men who were supposedly being lined up to replace him.

Kidd, who was assistant at Old Trafford between 1991- 98, was Ferguson’s blue-eyed boy, and when he left to carve out a career of his own at Blackburn, he seemed a certain candidate for a future vacancy in Manchester’s red quarter.

Instead, his 11-month spell at Ewood Park was a disaster – he led Blackburn from the top half of the Premiership to 19th in Division One – and he has not returned to management since.

McClaren’s fall from grace was not as rapid, but as every Englishman knows, it was every bit as dramatic.

Having replaced Kidd as Ferguson’s number two prior to Manchester United’s treble, the Yorkshireman was the progressive face of English management when he took over Boro in 2001.

His reign at the Riverside was relatively successful, even if he never fully endeared himself to the Boro fans, but his decision to take charge of England was a disaster.

McClaren failed to qualify for this summer’s European Championships, and his reputation was ruined in an instant. He has sought to rebuild it in Holland, and the early months of his reign at FC Twente have been reasonably positive.

But whenever managerial jobs in England appear, his name is rarely mentioned.

And if a gap was to emerge in the Old Trafford dug-out, it would be a massive surprise if he were to fill it.

With Kidd and McClaren out of the running, the current campaign began with four Manchester- United-managers-in-waiting working in the Premier League – Paul Ince, Mark Hughes, Steve Bruce and Keane.

Perhaps it is a coincidence, but it is interesting to note the extent to which the quartet have struggled.

Ince currently presides over a Blackburn side that are 19th in the table, and that have gone nine Premier League matches without a win. He is a short-priced favourite to be the next topflight manager to leave his post, despite only being appointed six months ago.

Hardly an ideal CV to present to the Glazers.

Hughes is slightly better placed, but despite leading the richest club in the world, the former United striker is still only 15th in the table.

He is working in uniquely difficult conditions, but with Abu Dhabi United Group demanding a rapid improvement in performances, it would not be a surprise if he was moved aside in the spring.

Bruce’s position at Wigan is not under immediate threat – 11th in the league is something of an achievement for a club of the Latics’ size – but his chequered career has included numerous highs and lows.

For quite a while now, the United link has hung heavy around his shoulders.

And then, of course, there is Keane.

Sunderland was supposed to be a staging post on a triumphant return voyage to Old Trafford. Instead, it looks like being both the beginning and the end of his odyssey.

He made plenty of mistakes on Wearside, but given the fate of his contemporaries, perhaps the most serious was his refusal to rule out a return to Manchester United.

Ryan Giggs and Gary Neville should be remember as much when they embark on their inevitable managerial careers.