Chris Huhne faces jail and political ignominy after he brought an end to years of denials and finally admitted that he has repeatedly lied about a motoring offence a decade ago.
The former Energy Secretary, 58, said he was resigning as an MP after he was warned by a judge that he should have "no illusions" about the extent of the punishment he faced for passing penalty points for speeding to his then wife. Huhne's change of heart – which was said to have come only on Sunday – emerged just a week after he denied perverting the course of justice in the same glass-panelled dock at Southwark Crown Court in London.
His last-ditch change of heart followed two failed attempts to have the case against him thrown out last month, when he argued that he could not have a fair trial. Legal commentators said he could now face a jail term of about six months when he is sentenced at a later date, although the offence can carry a life term.
"You should have no illusions whatsoever as to the sort of sentence that you are likely to receive, understand?" Mr Justice Sweeney told Huhne, who stood with his hands behind his back and nodded in response.
His decision to plead guilty ends the prospect of a public trial pitting the former minister against his ex-wife, Vicky Pryce. Their 26-year marriage ended acrimoniously following revelations of Huhne's long-running affair with his former press adviser, Carina Trimingham. Ms Pryce, who sat in the dock one seat away from Huhne during yesterday's hearing, is due to stand trial today for the same offence. She has denied the charge and claimed the defence of "marital coercion".
Ms Trimingham, 45, sat immediately behind him the dock, dabbing at her eyes as he pleaded guilty. As well as the ruin of his career, during which he twice tried and came close to securing the leadership of the Liberal Democrat Party, the multimillionaire has been left estranged from his family and facing a large legal bill after a case that is estimated to have cost about £500,000. Huhne employed a legal team headed by John Kelsey-Fry, QC, a highly regarded barrister who secured Harry Redknapp's acquittal last year when the football manager was accused of tax evasion.
A spokesman for the Crown Prosecution Service said: "We are currently calculating the costs incurred in this case and we are likely to make an application to the court for an amount of costs to be paid by Chris Huhne."
The extent of the family rifts caused by the case were laid bare in a series of text messages between Huhne and his youngest son, Peter, who called his father the "most ghastly man I have ever known" and threatened to tell police about the crime. On 21 May 2011, a few days before his parents were due to be questioned by police, Peter called on his father to "take responsibility" and said: "We all know that you were driving and you put pressure on Mum. Accept it or face the consequences."
Huhne declared the matter was something he would have to discuss with his mother. The teenager replied: "It's not about her – it's about your accepting responsibility to me."
In a brief statement outside court yesterday, Huhne announced that he intended to step down as an MP. He had quit the Cabinet a year ago, with a £17,000 severance package, when he was charged with the offence. "Having taken responsibility for something that happened 10 years ago, the only proper course of action for me is to resign my Eastleigh seat in Parliament, which I will do very shortly," he said.
A spokesman for the Liberal Democrat Party said Huhne intended to remove himself from the Privy Council and give up the title "the Right Honourable", which is granted to senior politicians, following the precedent set by other disgraced MPs such as Jonathan Aitken. There was no sign that he would hand back the severance package.
The charge stemmed from a journey Huhne made after he flew into Stansted airport on 12 March 2003, having worked at the European Parliament in Strasbourg for three days. A speed camera clocked his BMW travelling at nearly 20mph above the speed limit on the M11 late at night.
His then wife, Ms Pryce, agreed to take the points, even though Huhne accepted in a police interview that he could not remember her ever picking him up from the airport. She would have had to make an "extraordinary and pointless" 80-mile round trip to collect him while leaving the couple's children at home, according to the prosecution.
Huhne continued to protest his innocence even though Ms Pryce had her own car and he had his own free parking space at Stansted. In any event, the swapping of points to avoid a ban proved to be a futile gesture. He was disqualified later that year after police caught him using his mobile phone while driving.
The Liberal Democrat leader, Nick Clegg, said: "This is obviously an extremely serious matter and it is essential the legal process is now allowed to run its course. I am shocked and saddened by what has happened but I believe Chris Huhne has taken the right decision in resigning as an MP."
Huhne narrowly lost to Mr Clegg in a leadership election in 2007 and his assured handling of the energy and climate change brief, even after the break-up of his marriage, had seen him as a possible successor. The loss of his Hampshire seat raises the prospect of a clash between the Coalition partners in a marginal byelection. Huhne had a majority of 3,800 at the 2010 general election, but it is viewed as a key target for the Tories if they are to win an overall majority in 2015. There is also the prospect of Nigel Farage, the UK Independence Party leader, making another parliamentary run. He stood unsuccessfully in Eastleigh in 1994.
Legal experts say Huhne could face six months in jail when he is sentenced at a later date.
'I'm innocent': Huhne's denials
8 May 2011: Huhne's office denies claims that he asked someone "close to him" to take his speeding points so he could avoid a driving ban in 2003.
"The allegations made against Chris Huhne are simply incorrect. These allegations have been made before and have been shown to be untrue."
16 May 2011: He denies the allegations in a statement.
"They have been made before and have been shown to be untrue. I very much welcome the referral to the police as it will draw a line under the matter."
7 July 2011: Following questioning by Essex Police:
"There is no truth in those allegations and I very much welcome the police inquiry and I'm looking forward to them getting to the bottom of it and clearing it up. If cabinet ministers resigned every time wild allegations were made about them, you would find it difficult to get enough people around the cabinet table."
20 September 2011: "I'm delighted to say that there's an official inquiry into all of this stuff... I am expecting that the results... will draw a line under the whole matter and that will be the end of it."
3 February 2012: Facing criminal charges, Huhne resigns from the Cabinet:
"The CPS's decision today is deeply regrettable. I'm innocent of these charges and ... I'm confident that a jury will agree."