Five Conservatives breached the code of conduct over an “egregious” attempt to influence a former Tory MP’s legal proceedings, the Commons Standards Committee has found.

Theresa Villiers, Natalie Elphicke, Sir Roger Gale, Adam Holloway and Bob Stewart sought to interfere in a decision regarding ex-MP Charlie Elphicke, who was convicted of sex offences.

The committee recommended that former environment secretary Ms Villiers, senior Conservative Sir Roger, and Ms Elphicke should be suspended from the House for one day, while all five were told to apologise.

All five wrote to senior members of the judiciary raising concerns that a more junior judge was considering publishing character references provided for Mr Elphicke.

“The letters signed and sent by the members in this case were an attempt improperly to influence judicial proceedings,” the committee said.

“Such egregious behaviour is corrosive to the rule of law and, if allowed to continue unchecked, could undermine public trust in the independence of judges.”

The MPs’ behaviour was found to have “caused significant damage to the reputation and integrity” of the House of Commons.

Of the three recommended for suspension, two had “substantial legal experience” while the third, Sir Roger, is both the longest standing of the group and “still does not accept his mistake”.

They were all told to apologise to the Lord Chief Justice of England and Wales, as well as to the House.

Tory peer Lord Freud has already apologised over the letter after having also been found to have breached the code of conduct.

The parliamentarians wrote to senior presiding judge Lady Justice Thirlwall and Queen’s Bench Division president Dame Victoria Sharp, asking them to consider issues raised by the potential release of character references provided for Mr Elphicke.

Written on headed House of Commons notepaper, the letter was also copied to Mrs Justice Whipple, who had heard the case and was deciding whether to release the references.

Ms Elphicke, Mr Elphicke’s estranged wife and his successor as Dover MP, apologised but raised concerns about the committee’s ruling in a statement.

“My actions were solely motivated by my duty to represent my constituents who had raised serious concerns with me. Those who approached me about this matter were private individuals who I believe have no place in the public eye,” she said.

“It is of deep concern to me that the committee did not fully recognise this.

“However, as I have already acknowledged, I do recognise that there were faults in the way I set about raising my constituents’ valid concerns. I regret and apologise for that and will learn from this experience in the future exercise of my duties as an MP.”

Ms Villiers’ spokesman said she accepts the committee’s findings and she “deeply regrets the mistake” of signing the letter.

“She has apologised sincerely for doing this. The correspondence was well-intentioned, but Ms Villiers recognises that it was wrong to raise this matter with judges when a court hearing was pending,” the spokesman added.

Sir Roger declined to comment on the ruling, but he told the committee during evidence: “I would find a different way of doing it, but would I do it again – would I seek to achieve the same effect? Yes, I would.”

Mr Elphicke was jailed for two years in September last year after being convicted of three counts of assault against two women.

One of them said he had asked her about bondage and sex, then kissed her and groped her breast before chasing her around his home, chanting: “I’m a naughty Tory.”

In December 2020, Mrs Justice Whipple agreed to a representation by the media to release the identities of those behind the character references.

Labour’s shadow Commons leader Thangam Debbonaire said: “Whether it is trying to interfere in judicial matters or sexually harassing their staff, the (Standards Committee) report today into the conduct of a gang of Conservative MPs once again shows that the Government and their MPs think it is one rule for them and another for everyone else.

“This behaviour is corrosive and does nothing but undermine trust in Parliament and it must not be allowed to continue.”

Clarification: An earlier version of this article incorrectly stated the MPs had sought to interfere with the trial of Charlie Elphicke when in fact they had written to a judge ahead of sentencing, we are happy to clarify this.

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