Warburton formally quits as MP over cocaine use and harassment allegations

The decision means Rishi Sunak faces another potentially difficult by-election in the Somerton and Frome seat vacated by the former Tory MP.

Mr Warburton had announced his resignation on Saturday, hitting out at the “cripplingly glacial pace” of the investigation into his conduct, which has already taken 14 months.

His exit from the Commons was confirmed on Monday with his appointment as Steward and Bailiff of the Manor of Northstead – one of the procedural routes for an MP to quit.

The former MP has admitted cocaine use, telling GB News on Monday he had made “a ridiculous decision and a silly mistake”, and claiming he had been “led down a pathway”.

He said: “I was caught, I was photographed, deliberately set up and I feel for it. It was naivety and stupidity. There’s no question about that.”

In an interview with the Mail on Sunday, Mr Warburton said he had taken cocaine after drinking “tons of incredibly potent” Japanese whiskey, but denied claims he harassed a female political aide in his Westminster flat.

Mr Warburton’s resignation will trigger an electoral battle in his Somerset constituency, adding to Rishi Sunak’s problems as the prime minister faces at least two other by-elections following the resignations of Boris Johnson and Nigel Adams.

A fourth MP, Nadine Dorries, as also announced her intention to resign but has not yet done so formally.

Mr Warburton told GB News the Government faced a “tough” contest in his seat, where the Liberal Democrats will look to overturn the Tories’ majority of 19,213 and win back a seat they held between 1997 and 2015.

He said: “It’s going to be tough for them. I mean, I’ve won three large majorities in a row, but prior to that it was a Lib Dem seat for 18 years over four elections.

“It’s going to be difficult and the Government is obviously facing three other by-elections … it’s a tough time for by-elections.”

When he announced his resignation on Saturday, Mr Warburton hit out at the investigation conducted by Parliament’s Independent Complaints and Grievance Scheme (ICGS), claiming he had been denied a fair hearing.

In his resignation letter he said had been left with “no choice” but to provoke “the upheaval of a by-election”, adding: “It is my hope that, in so doing, I can freely illuminate the methods of an oversight system not fit for purpose, so that friends and colleagues in the House can see the perverted process by which their own judgment may at any time be freighted.”

A House of Commons spokesman said: “Parliament remains absolutely committed to the ICGS.

“It is there to ensure that all complaints are dealt with in a manner that is fair, thorough, independent and efficient, offering support to all parties.

“The target to reduce the length of investigations must always be balanced against the paramount requirement to ensure that investigations are rigorous and robust.

“The scheme always seeks to learn from cases and is mindful of the impact investigations may have on those involved.”

The spokesman refused to be drawn on Mr Warburton’s specific case as confidentiality requirements meant “we cannot provide any information on any complaints or cases, including whether or not a complaint has been received”.