Having survived weeks of scrutiny following accusations of racism during his time in charge of England, Sampson was fired after FA bosses became aware of the details of “inappropriate and unacceptable behaviour” at former club Bristol Academy.
The shock announcement was made by FA chief executive Martin Glenn less than 24 hours after Sampson presided over England’s 6-0 win over Russia in a World Cup qualifier.
In a statement, sports minister Tracey Crouch said: “This situation is a mess and raises very serious questions about whether the historic processes that the FA had in place around the recruitment of coaches were appropriate, for something like this to have been missed.
“The FA are right to have taken action but reassurance is needed to make sure this does not happen again at any level of coaching.”
The details of Sampson’s improper behaviour have not been made clear but they are understood to involve a relationship with a player, although there is no suggestion of any criminal wrongdoing.
In the statement which confirmed Sampson’s fate, the FA explained that “safeguarding allegations” were made against him soon after he was given the England job in December 2013.
Those allegations were investigated by the FA’s safeguarding unit and “its assessment was that he did not pose a risk working in the game”.
However, senior FA officials did not read the unit’s report until last week, having been alerted to its contents by undisclosed sources. It was only then that Glenn brought it to FA chairman Greg Clarke’s attention and it was discussed by the board over the weekend and into Monday.
Having learned what Sampson was accused of at Bristol, the board decided it was enough to terminate his contract but not until after the game at Tranmere on Tuesday, when his players put on a very public show of support.
Speaking to reporters at Wembley, Glenn said this was the “most awkward and complicated issue” he has had to deal with but stressed it is separate to the ongoing investigation into England and Chelsea star Eni Aluko’s claims about Sampson using racist language to her and team-mate Drew Spence.
On the issue of what Sampson has been sacked for, Glenn said: “Let’s be really clear: no laws were broken.
“Greg (Clarke) and I are not able to challenge the professional views of our safeguarding experts. We thought the conduct issues raised in the report were what the problem was.
“We felt that during his time at Bristol, Mark had overstepped the professional boundaries between player and coach. We both agreed that Mark’s position was untenable and we shared it with the board over the weekend.”
Where this leaves the 34-year-old Welshman is anybody’s guess but it is understood his former club, now known as Bristol City Women, were not even aware of the outcome of the FA investigation until Wednesday’s dramatic announcement or know the identity of the player involved.
A club source said it was “a shock” to learn Sampson had lost his job and the FA had not contacted them about the case.
As Crouch said, the FA itself will now have to answer what due diligence they did on Sampson in 2013, why he was not sacked once his conduct had been established and why senior officials did not review this case while wholeheartedly defending him against claims of bullying and discrimination over the last 18 months - a defence that cost them an £80,000 settlement with Aluko.
Technical director Dan Ashworth, already under fire for his handling of the initial complaint Aluko complaint, will face questions about his recruitment methods, while Glenn has already hinted he feels let down by the FA’s safeguarding team for the “very perfunctory” verbal report they gave him on its Sampson investigation.
The Sampson issue coming at a time the FA is under huge pressure for its response to historic cases of child sex abuse only adds to the sense of crisis.
Then there is still the issue of Sampson’s alleged use of racist language. The FA is maintaining the line he has twice been cleared of wrongdoing in that regard but the quality of those investigations has been questioned by anti-racism campaigners, politicians and the Professional Footballers’ Association.
And the second of those investigations, led by independent barrister Katharine Newton, has effectively been reopened by a new statement from Spence.
With Aluko and fellow Sampson critic Lianne Sanderson scheduled to appear before the inquisitors on the Digital, Culture, Media and Sport committee next month, the FA can expect further trials.