The 53-year-old looked to have survived the worst of the intense pressure which came his way as the Magpies' season lurched from one crisis to another.

However, just four days after they avoided an FA Cup giant-killing act - if only just - at Stoke on Sunday, owner Mike Ashley and chairman Chris Mort decided the time was right to act.

Confirming that manager and club had parted company by mutual effect with immediate effect, Mort said in a statement released on the club website, www.nufc.co.uk: "Mike and I would like to place on record our thanks for Sam's efforts and wish him well for the future.

"A new manager has not yet been appointed at Newcastle United.

"We will make a further announcement on the managerial position when appropriate."

Coach Nigel Pearson, as he did following Glenn Roeder's departure in May last year, will take charge for Saturday evening's daunting trip to Manchester United, but the book on Allardyce's successor already has an overwhelming favourite.

Geordie hero Alan Shearer, who scored a record 206 six goals for the club in a glittering 10-year career at St James' Park, has massive public support - he was being quoted on Wednesday at 4-6 - and the word on Tyneside was that a British manager is being targeted.

That would obviously rule out former Chelsea boss Jose Mourinho, whose name has been mentioned in recent days.

Shearer, who is currently out of the country on holiday, has been studying for his coaching qualifications for several years and would need only to be enrolled on the UEFA Pro-Licence course to be allowed to manage in the Barclays Premier League.

The news came as a huge surprise to Allardyce, who conducted his pre-match press conference for the United game this afternoon.

In the official statement, he said: "I am disappointed to be leaving Newcastle United, but I wish the club all the best for the remainder of the season and for the future."

Hours earlier, he had once again spoken of the need for managers to be given time, and little can he have known just how quickly his was running out.

Asked if the pre-eminent manager of his era, Sir Alex Ferguson, was the classic example of that, he replied: "Every manager who has been successful has been given the time to put his dynasty into place. David Moyes is the same, Arsene Wenger is the same.

"The trouble is today, that amount of time is no longer available.

"That is plain and clear for everybody to see, otherwise seven managers would not have already been sacked in the Premier League this year."

That figure has now become eight and one of the most precarious jobs in a precarious profession is up for grabs once again.