The trustees of the Presidents Club were in breach of "key charity law duties" when they hosted a black tie event at The Dorchester Hotel, a report has concluded.
The controversial Presidents Club event saw women, hired through an agency, told to wear black underwear and "sexy" black shoes to work as hostesses for their shift.
Undercover reporting from the Financial Times revealed alleged incidents of sexual harassment from those on the all-men guest list at the fundraising event, which auctioned off sports cars and lunches with politicians.
The Presidents Club scrapped all planned events after the video footage and report emerged, and said it would distribute money raised among various charities.
A Charity Commission report into the event said: "The trustees failed fully to recognise or address risks to the reputation of the charity – and its purpose of raising money for good causes – arising from holding an all-male event staffed by female-only event staff, who were subject to instructions on their appearance, including that they wear 'smart, sexy shoes'."
The commission added the failure of the trustees to put "clear or adequate procedures" in place to deal with harassment allegations was in "stark contrast" to the privacy it granted those on the guest list.
But the report does say there is no evidence to suggest the trustees acted in "bad faith" or with anything other but the best interests of the charity at heart.
Helen Stephenson, chief executive of the Charity Commission, said: "The allegations made about the event were entirely at odds with what we would expect from any charity when raising funds for such important causes.
"Our report should serve as a warning to others that raising funds for charity does not absolve trustees of their legal duties or moral responsibilities."
The commission admitted no one else came forward with allegations after it called for information after the Financial Times report.
A spokesman for the trustees said: "We are also surprised at both the report's muted acknowledgement of the fact that not a single complainant has come forward since the FT's article was published, and at the weight of credibility it gives to the FT's reporting of the 2018 dinner.
"The core issues investigated by the Charity Commission in coming to its conclusions concern perceptions rather than any proven facts. We, as trustees, have never and would never condone the sort of alleged behaviour described in the FT article."
The trustees, named on the Charity Commission website as David Meller, Harvey Soning and Bruce Ritchie, said they would comply with the action plan in the report.
Hosts were reportedly told to wear skimpy black dresses and matching underwear, with one told by a guest she was "far too sober". He then declared: "I want you to down that glass, rip off your knickers and dance on that table."
The event was dubbed a "lady zoo" for "slimeballs" by furious MPs, with minister Anne Milton admitting: "Words fail me."
Mr Meller is the chairman of the Meller group, a luxury home and beauty supplier. He was also a non-executive board member for the Department for Education until January.
Mr Soning, 72, is a property developer who chairs the James Andrew agency, which he founded in 1974.
More from UK
Mr Ritchie is the chief executive of the Residential Land Group and was previously the joint owner with Marco Pierre White of the White Star Line restaurant group.
Over 33 years, the Presidents Club's dinners had raised around £18m for charities including Great Ormond Street Hospital.