Huhne and the wife he left to be reunited – in a court

Energy Secretary resigns from Government after being charged with perverting course of justice

Chris Huhne and his estranged wife, Vicky Pryce, are to be reunited in a Crown Court dock after England's most senior prosecutor ruled there was enough evidence to charge them both with perverting the course of justice.

Shortly after 10am yesterday, Mr Huhne became the first serving cabinet minister to resign to fight criminal charges, after an eight-month police inquiry. He will now appear alongside Ms Pryce at Westminster Magistrates' Court a week on Thursday. If they are eventually found guilty both face jail.

Mr Huhne phoned his party leader, Nick Clegg, minutes after being informed by prosecutors that they intended to charge him in relation to allegations that he persuaded Ms Pryce to take speeding points on his behalf in 2003 to stop him losing his licence. The allegations came to light after the couple split acrimoniously after 26 years of marriage.

Mr Cameron was informed as he travelled to an engagement in the West Country and later had a five-minute phone call with Mr Huhne in which the Energy and Climate Change Secretary confirmed he was standing down.

The Independent understands that Mr Clegg and Mr Cameron had already made contingency plans, which were immediately put in place. Mr Cameron called Ed Davey, the Liberal Democrat Business minister, and offered him Mr Huhne's job. Norman Lamb, Mr Clegg's Parliamentary Private Secretary, was offered Mr Davey's job.

Despite the carefully orchestrated attempt to portray "business as usual", senior Liberal Democrats were deeply perturbed at the decision to prosecute. Not only does the decision rob the party of one of its most able ministers, but some close to Mr Clegg fear that if Mr Huhne is cleared he could become a potential threat to the leadership.

In his letter accepting Mr Huhne's resignation, Mr Clegg was careful to keep the door open for his return. "I fully understand your decision to stand down from government in order to clear your name," he wrote. "But I hope you will be able to do so rapidly so that you can return to play a key role in government as soon as possible."

Mr Huhne told Mr Clegg he had "concluded that it would be distracting both to my trial defence and to my official duties if I were to continue in office as a minister". It is not yet clear whether Mr Huhne, who is a self-made millionaire, will accept the £17,200 severance payment he is entitled to as an ex-minister. Labour called for him to give up the payment, but his own party insisted it was a personal matter.

Mr Davey's promotion maintains the proportions of Conservatives and Liberal Democrats in the Cabinet that were agreed in the 2010 coalition negotiations. But some environmental groups are nervous that he is not as "big a hitter" as Mr Huhne, who successfully fought George Osborne over the Green Investment Bank and persuaded the Government to sign up to the fourth carbon budget. Mr Clegg's aides insisted that Mr Davey had proved himself an effective minister who will continue Mr Huhne's agenda. "He has a different style from Chris," one said. "But then, most people do."

In a televised news conference, the Director of Public Prosecutions, Keir Starmer, said that having reviewed the evidence, the Crown Prosecution Service believed there was enough to bring charges: "The essence of the charges is that, between March and May 2003, Mr Huhne, having allegedly committed a speeding offence, falsely informed the investigating authorities that Ms Pryce had been the driver of the vehicle in question, and she falsely accepted that she was the driver."

Describing the prosecution as "deeply regrettable", Mr Huhne, 57, said: "I am innocent of these charges and I intend to fight this in the courts and I am confident that a jury will agree." He made clear that he will remain MP for Eastleigh in Hampshire while he awaits trial.

Ms Pryce, a prominent economist, told the BBC she hoped for a "quick resolution" to the case, adding that "it would not be appropriate to comment further at this stage".