Southampton Football Club left a paedophile youth coach "free to continue" his abuse of boys, an independent report has found.
Bob Higgins was jailed for 24 years in 2019 for sexually touching trainees in the 1970s and 1980s.
A report by Barnardos, commissioned by the club, said its board should have acted on rumours about Higgins which "seemed to be rife".
The club said it had "no excuse" for the failure to act.
Higgins was found guilty of 46 counts of indecent assault on 24 victims, predominantly Southampton and Peterborough United trainees, between 1971 and 1996.
Former trainees described being abused during massages, in Higgins car, at training camps and while staying at his house.
Among its conclusions, the report by the childrens charity found there was "no managerial oversight" of boys staying overnight at Higgins home, and the board had been "neglectful" in not addressing the issue.
The report also highlighted that concerns had been raised about Higgins behaviour over a number of years.
It said the board was made aware of a complaint against Higgins in 1979, shortly before he left the club for a period, but there was no detail available about its nature or the clubs response.
The report also said a letter from the chairman of the Football Association in 1987 raised issues that would have caused "disquiet".
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It said the board "took no action, leaving boys vulnerable and Higgins free to continue abusing them".
"Despite assertions to the contrary, the board and/or management must at some point have heard or been told about stories circulating about Higgins and if this was so, they failed to take any action to find out whether there could be any substance to the rumours," it said.
"By not doing so, either intentionally or by default, the club failed to put the safety and welfare of boys concerned first."
It said it could not conclude with any certainty who knew about the rumours and that the boys themselves did not report abuse to other adults.
Higgins left the club two weeks after Dave Merrington, who was the youth team manager at the time, overheard players making "troubling comments" about him in April 1989.
The Barnados report said when his alleged sexual abuse of boys was brought to the boards attention, it did not immediately inform the police - something which it called a "dramatic let-down" for those involved.
It said the club "persistently failed in exercising a duty of care" towards the boys.
"This left them and other boys vulnerable to ongoing abuse by Higgins which impacted upon their lives as children and the adults they became," it said.
Those abused were "offered no support and were left to make sense for themselves of all that happened", it added.
In its response to the report, Southampton FC said there had been a "complete institutional failure" on its part.
A statement said: "It is very clear that the club completely failed to protect so many young people from suffering abuse over a long period of time.
"This failure was then compounded by the complete lack of support for those boys who were brave enough to speak up about the abuse. There is no excuse for that.
"It cannot be possible that anyone could fail to regard any coach having so many children stay at their house or engage in so many extremely odd behaviours around children as highly unusual and inappropriate."
Dean Radford, who was abused by Bob Higgins as a Southampton youth player from the age of 13, said the reports conclusions were "completely damning".
He said: "Theres no reasoning behind why they wouldnt have reported these allegations about Higgins or investigated at least.
"The heartbreaking thing is that if something had been done then then none of these lads would have been affected.
"I do believe now that Southampton Football Club are doing the right thing, I think the people that are involved now have set things in place and they take this sort of thing very, very seriously."
Earlier this year, a report by Clive Sheldon QC into sex abuse in football said a headteacher warned the club about Higgins in the 1970s but it was dismissed as "malicious gossip".
That report also said Southampton could have reported an allegation of abuse to police "more quickly" and failed to carry out any of its own inquiries at the time to find out if other boys may have been victims.