FORMER Cabinet minister Sir Geoffrey Cox could face an investigation by the Commons standards tsar over claims he “broke the rules” by using his parliamentary office for his second job offering legal advice.

The Times reported that the former attorney general, who has faced criticism over his outside earnings, used his Westminster office to participate remotely to advise the British Virgin Islands in a corruption probe launched by the Foreign Office.

Conservative MP and QC Cox has earned hundreds of thousands of pounds for his work with the islands, while allegations have surfaced that he was based in the Caribbean earlier this year while using lockdown proxy voting rules to continue to have his say in the Commons.

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Deputy Labour leader Angela Rayner said the alleged use of the office appeared to be “an egregious, brazen breach of the rules” and has written to standards commissioner Kathryn Stone asking her for “guidance on beginning a formal investigation on this matter”.

Rayner said in her letter that the MP’s code of conduct was “very clear” that elected representatives ensure that “any facilities and services provided from the public purse is … always in support of their parliamentary duties” and “should not confer any … financial benefit on themselves”.

She added: “The member has clearly broken this rule based on the media reports we have seen.

“Members must be clear that they cannot use the estate for private financial gain and where there is such a stark conflict with public interest, they must face substantial consequences.”

Cox has since defended himself, claiming that he "does not believe" he broke the rules.

He said the chief whip had signed off on his use of using remote voting before going to the Caribbean.

A statement posted on Cox's parliamentary website said: "Sir Geoffrey regularly works 70-hour weeks and always ensures that his casework on behalf of his constituents is given primary importance and fully carried out.

“Throughout this period, he continued to have online meetings with organisations, businesses and individuals within the constituency and it made no difference where he was for that purpose since it was not practicable or desirable at that time to meet face to face.

“As to the use of the proxy, prior to his visit to the BVI, he consulted the Chief Whip specifically on this issue and was advised that it was appropriate.

"As for the allegation that he breached the parliamentary code of conduct on one occasion, on September 14 2021, by being in his office while participating in an online hearing in the public inquiry and voting in the House of Commons, he understands that the matter has been referred to the Parliamentary Commissioner and he will fully cooperate with her investigation.

“He does not believe that he breached the rules but will of course accept the judgment of the Parliamentary Commissioner or of the committee on the matter.”

The most recent register of financial interests showed that Torridge and West Devon MP Cox will earn more than £800,000 from Withers, an international law firm appointed by the British Virgin Islands (BVI) government in January.

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Cox also disclosed in the register that from September 28 this year until further notice, he will be paid £400,000 a year by Withers for up to 41 hours of work per month.

In the British Virgin Islands commission of inquiry hearing on September 14, Cox can be heard in the online recording telling the commissioner: “Forgive my absence during some of the morning – I’m afraid the bell went off.”

The bell referred to could be the division bell that sounds off across the parliament estate to alert MPs to a vote taking place.

Earlier in the proceedings, Cox appears to vacate his seat for about 20 minutes at around the two-hour mark in the video footage.

His Commons voting record shows that he voted in person on six occasions on September 14 to push through the Government’s health and social care levy.

Rayner said: “This appears to be an egregious, brazen breach of the rules.

“A Conservative MP using a taxpayer funded office in Parliament to work for a tax haven facing allegations of corruption is a slap in the face and an insult to British taxpayers.

“The Parliamentary Commissioner for Standards must investigate this, and the Prime Minister needs to explain why he has an MP in his parliamentary party that treats Parliament like a co-working space allowing him to get on with all of his other jobs instead of representing his constituents.

“You can be an MP serving your constituents or a barrister working for a tax haven – you can’t be both and Boris Johnson needs to make his mind up as to which one Geoffrey Cox will be.”

The row over second jobs comes in the wake of a recommendation that former environment secretary Owen Paterson should be suspended for six weeks after the Commons Standards Committee found he had broken the centuries-old ban on paid lobbying by MPs.

In the bitter aftermath of the row, Paterson announced he was quitting as MP for North Shropshire after 24 years, as an attempt by the UK Government to delay his punishment by ripping up the current standards system failed when opposition parties refused to offer their support.

Boris Johnson, who was previously well paid as a backbencher, including for his regular Daily Telegraph column, signalled that those in the Commons should focus on their electorates.

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A spokesman for the Prime Minister, while refusing to be drawn on individual cases, said Johnson thought an “MP’s primary job is and must be to serve their constituents and to represent their interests in Parliament”.

The No 10 spokesman said: “They should be visible in their constituencies and available to help constituents with their constituency matters.

“If they’re not doing that, they’re not doing their job and will rightly be judged on that by their constituents.”