A former hostess at the "slimeball gala" has told how she was given a tight fitting black dress that showed "everything" in the right light to serve wealthy businessmen.
The 25-year-old who worked last year, says she was offered cocaine at the dinner where at least four men asked her to go upstairs to their rooms at The Dorchester Hotel for sex.
She told MailOnline: "When I arrived I was ordered to sign a non-disclosure agreement preventing me from talking about what went on at the event.
"Then I was given a glass of wine. I have never been given alcohol before starting work before.
"When I got down on the event floor I turned to another girl and said: 'What are we supposed to do now?' She said, 'Just enjoy the party. Talk to some of the guys.'
"There were men everywhere. Girls were sat on guys" laps. Champagne was poured into girls' glasses.
"Four guys came up to me saying 'I have a room upstairs, come up. I was being offered coke. By then I realised this wasn't a normal posting, it was a whore party.
"I felt we were expected to have sex with these men.
"I said to a supervisor who runs it that this was not what I expected. I said that I felt uncomfortable and said I wanted to go home.
"She said: 'Don't be silly. Go and have a drink, they are lovely and they have lots of money.'
"I saw quite a few girls leave and go to the lift with some of the guys there."
The unnamed hostess, from London, who was paid £90 ($174) for the shift, said her and several of the other women hid in the toilets until their shift finished at 1am - but they were ushered back onto the event floor by party organisers.
She added: "I said I didn't want to, but she wasn't listening. I have a boyfriend. I didn't want to have sex or take drugs."
The hostess said that before the event she emailed the agency boss Caroline Dandridge, who replied and agreed to meet her in a Mayfair bar.
According to the FT, the task of finding women for the dinner is entrusted to Caroline Dandridge, founder of Artista, an agency specialising in hosts and hostesses for what it claims to be some of the "UK's most prestigious occasions" .
At their initial interviews, women were allegedly warned by Dandridge that the men in attendance might be "annoying" or try to get the hostesses "p****d", the FT reported.
She allegedly said, at 5ft 2in, the girl was probably too short for the party.
But later Dandridge emailed the woman to say the client had seen a picture of her face and wanted her to attend despite her height.
She said she arrived and had her hair and makeup touched up before being sent out to the party.
The hostess added: "I felt uncomfortable and would never do it again."
In a statement the Dorchester said it had a zero-tolerance policy regarding harassment of guests or employees.
The Presidents Club said: "The allegations will be investigated fully and promptly and appropriate action taken."
Dandridge said: "There is a code of conduct that we follow, I am not aware of any reports of sexual harassment and with the calibre of guest, I would be astonished."
Prime Minister Theresa May last night condemned "appalling" sexist behaviour at the men-only charity gala.
Downing Street said reports of scantily-clad female hostesses being flashed and groped at the dinner showed there was "a long way to go to ensure all women are treated properly as equals".
Children and families minister Nadhim Zahawi was struggling to save his career yesterday, after joining 300 guests at the fundraiser in the Mayfair hotel, where they were served by 130 "tall, thin and pretty" waitresses.
It was claimed last night that prostitutes were at the event where billionaires bid up to £400,000 for lots including a night at a strip club, tea with Bank of England governor Mark Carney, and lunch with Boris Johnson.