11/04/2014 04:07 BST | Updated 11/04/2014 04:59 BST

The Palace Of Sexminster: Young Staff Reveal Alcohol-Fuelled Sexual Harassment Rife In Parliament

A third of young aides claim to have been victims of drunken MPs, it can be revealed following the conclusion of the Nigel Evans trial.

A shocking new investigation has cast a shadow over the reputation of MPs yet again, after it revealed allegations of exploitation and a sordid abuse of power from some in the House Of Commons.

A small group of MPs is said to have regularly become drunk and made passes at male researchers in particular, Channel 4 reported in a programmed shown last night to coincide with the end of the Evans trial.

His trial had already showcased the questionable sexual politics at play in Westminster and although the MP was cleared of all nine charges of rape and sexual assault, the former Commons Deputy Speaker admitted his involvement with a man 33 years his junior, who had previously done work experience in Westminster.

The court heard how Evans had been the “high watermark of over-friendly, inappropriate behaviour by a drunken man” but did not amount to any criminal offence.

The exploitation of vulnerable young parliamentary researchers by predatory MPs is being "brushed under the carpet" by the main political parties, one of Evans' alleged victims claimed.

He accused the parliamentary authorities of ignoring a problem that was widespread at Westminster.

"I don't think any of the main parties know what to do. The strange (thing) about Parliament is that they make the laws but they don't act like any other place of business," the man, who has not been named, told BBC2's Newsnight.

Westminster’s sexual harassment culture recently came under intense scrutiny last year after the Lord Rennard affair, when the senior Liberal Democrat was accused of sexually harassing women party activists.

Channel 4 has now revealed that other, mainly Conservative, MPs regularly got drunk, “flirted” and made passes at young male parliamentary workers during Commons drinking sessions.

One unidentified man spoke of how he was approached to “go to the Gents” with an MP at an event for young political activists while another man described how an MP invited his entire office staff to a gay bar.

"The MP suggested I go to the toilets with him at about 1am, but then at 3am I saw him going back to his hotel room with a guy who looked about 18," one said.

The Channel Four investigation showed that young men are more likely to get harassed than women with two in five young male workers having received unwanted sexual advances.

One woman described watching the abuse of power happening.

"I watched men coming on to men, and men hiring men that they wanted to sleep with. I saw male MPs and researchers having relationships.

"When I was there, older men would explore their sexuality and be predatory to younger men."

Last night, as the allegations emerged, the Tories announced they were implementing a new code of conduct and a grievance procedure for MPs and their office staff.

The code will set out in clear terms how MPs are expected to behave in their offices. It will remind them of their rights and responsibilities as employers, making clear that their staff should be treated with respect.

Secretaries and researchers should also be able to work in an environment “free from harassment and bullying, and inappropriate language”, the party said.

Commons Speaker John Bercow has also set up a helpline for staff of MPs from all parties.

But the Channel 4 News investigation claimed one Conservative MP recently expressed the view that those who believe themselves to be victims of unwanted sexual advances should toughen up – or as the MP put it: "Grow a pair."