Glenn confirmed that Sampson was found to have "an issue about the relationship between coach and players" that was "unacceptable", but the Women in Football group issued a statement on Thursday to express their concern that Sampson was initially given the job back in 2013 when these allegations were first brought to the attention of the FA.
Mark Sampson, who led England to third place at the 2015 World Cup, was dismissed after the Football Association leadership became aware of the full extent of an investigation into his conduct at Bristol's Women's Super League club.
But Sampson's tenure was marked by accusations of impropriety that first arose only months after he was hired in December 2013, and on Wednesday - less than 24 hours after his team began qualification for the 2019 World Cup with a 6-0 win over Russian Federation - the English Football Association fired him, citing "clear evidence of inappropriate and unacceptable behaviour" in a statement announcing its decision.
A 2015 FA assessment found Sampson, who was appointed England boss in December 2013, did not pose a risk.
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 Russian Federation in a World Cup qualifier.
"Women in Football [WiF] are deeply concerned by the revelations surrounding Mark Sampson's employment as England manager", the statement read.
The 34-year-old was sacked as England Women's manager on Wednesday, a day after leading the team to a 6-0 win over Russian Federation, for "inappropriate and unacceptable behaviour" in his previous role at the Bristol Academy.
Glenn said that he chose to fire Sampson after he was given the full report of the probe last week.
Sampson had been involved in a dispute with Chelsea and England ladies striker Eniola Aluko after she accused him of "bullying and harassment" in 2016.
"I don't know too much about it and I'm sure we'll find out the full story in time to come". "We felt during his time at Bristol, Mark had overstepped the professional boundaries between player and coach". "WiF understands that questions over Sampson's suitability for the role were flagged to the FA as early as 2013 during the recruitment process".
Collins said: " I think he (Glenn) has got hard questions to answer.
'We have seen the information and decided the conduct was not what we want from an FA employee'.
His contract has been paid up in full by the FA.
Brooking, who retired from The FA in June 2014, was part of Sampson's interview process but insists that he had no cause for concern at the time.
In recent weeks Spence has come forward to corroborate Aluko's version of events and criticised the investigations that cleared Sampson for not seeing fit to interview her about the accusations.
Collins, chairman of the Culture, Media and Sport Select Committee, last night said: "If it transpires that FA executives had warnings and advice that they didn't follow up, then their positions become untenable".