Boris Johnson risks losing his election gains against Labour if he does not clean up the “shameful” Westminster lobbying controversy, a Conservative grandee has warned.

Sir Bernard Jenkin, chair of the Commons Liaison Committee – made up of senior MPs, has urged the Prime Minister to get a grip on the lobbying system following a series of revelations in the wake of Greensill Capital’s collapse into administration.

A failure to be “more transparent” than previous administrations could risk the so-called “red wall” seats that Mr Johnson built his 2019 majority on, Sir Bernard suggested.

A series of probes have been commissioned, including by Downing Street, as Westminster looks to understand the role former prime minister David Cameron played in securing Whitehall access for Greensill, which was selected to delve out Government Covid support loans at the start of the pandemic and whose collapse now risks thousands of jobs, particularly in the steel sector.

The saga deepened last week after it emerged the former head of government procurement, Bill Crothers, took a part-time position with the failed firm while in his Whitehall post.

Writing in The Observer, Sir Bernard said the “lines between public service and private gain” had become “blurred”.

The senior Tory described the current situation as “shameful” and “utterly corrosive of public trust in government”.

In an apparent dig at the former Remain-backing Cameron government, he added: “This should matter to Boris Johnson.

“He does not need to pretend to be a saint, but his ‘red wall’ voters, who gave him his majority, will start to dismiss him unless he can show he is more open, more transparent and very different from the out-of-touch elite he defeated in the 2016 referendum and ousted from government.”

Sir Bernard Jenkin
Sir Bernard Jenkin (UK Parliament/Jessica Taylor)

Sir Bernard’s theory will be put to the test in only a few weeks as Mr Johnson looks to see whether he can turn Hartlepool, a seat traditionally held by Labour, blue during the by-election on May 6.

Labour is determined to keep the lobbying issue alive, reportedly believing the issue of Tory sleaze in Westminster is cutting through to voters.

The controversy over the relationship between Government and the private sector follows disclosures that Mr Cameron personally lobbied Chancellor Rishi Sunak on Greensill’s behalf and was able to arrange for its founder, Lex Greensill, to have a “private drink” with Health Secretary Matt Hancock.

Senior figure Anneliese Dodds has written to Mr Sunak setting out 21 questions the Opposition party wants answers to over his dealings with the former Tory leader and Greensill.

The questions include asking for more information about the “proposals” mentioned by Mr Sunak in a text to Mr Cameron and why a further meeting between Greensill and Treasury officials took place on May 14 2020 “at the Chancellor’s request”.

In her letter, Ms Dodds told Mr Sunak that she was “concerned” his dealings with the former No 10 incumbent “may have constituted a breach of the ministerial code”.

David Cameron has been at the centre of a storm over government lobbying
David Cameron has been at the centre of a storm over government lobbying (Jacob King/PA)

“The Chancellor is running scared of scrutiny over his role in the Greensill affair, but the public demand answers,” said Ms Dodds.

The Sunday Times reported that Mr Cameron was able to assist the specialist bank in securing a lucrative NHS contract after he contacted a civil servant who had served under him in the Cabinet Office.

The newspaper said Mr Cameron emailed Matthew Gould last year, who had since moved on to head NHSX, the health service’s digital arm, about rolling out Greensill’s advance payment app, Earnd, for doctors and nurses across the NHS,  a move that proved successful.

The former Tory party leader has insisted he did not break any rules through his dealings but acknowledged there are “lessons to be learned”, and that as a former prime minister, any contacts with Government should be through the “most formal channels”.

With the official mourning period over following the Duke of Edinburgh’s funeral on Saturday, ministers are likely to face a barrage of questions about the Greensill affair in the media as the Government returns to putting up senior figures for interviews.

Environment Secretary George Eustice, a former press secretary to Mr Cameron while he was opposition leader, is set to take questions on Sunday morning – the first time a minister has been in the broadcast hot seat since the news of Philip’s death was announced.