While the lengthy delay was condemned as “outrageous”, Tony Blair continued to insist that Mr Clarke should remain in office as he tried to avoid a bloody political upheaval in the run-up to this week’s local elections.

The Times has learnt that Mr Blair has ruled out any change now because he fears even more political turmoil would be triggered by the loss of either the Deputy Prime Minister or the Home Secretary — two of the heavyweights in the Government.

John Prescott was the subject of more embarrassing claims yesterday after his former assistant diary secretary Tracey Temple gave graphic details of their two-year affair to The Mail on Sunday.

Labour MPs and party canvassers have warned Downing Street that the prisoner release fiasco is playing particularly badly on the doorstep.

The new disclosure that Mr Clarke failed to tell Mr Blair as soon as he knew about the extent of the problem will not only lead to further dismay within the party as Thursday’s polls draw nearer but revive questions about Mr Clarke’s position. David Davis, the Shadow Home Secretary, said yesterday: “How many more serial errors of judgment can the Home Secretary make to put the public at risk? It is outrageous that he did not tell the Prime Minister for three weeks.”

The release of the 1,023 prisoners, the most serious lapse in penal policy since Labour came to power in 1997, has dominated the last few days of the local election campaign. “It’s all about Charles Clarke and the prisoners. People will not look us in the eye,” one Labour MP said.

A 40-year-old mother, who was dragged from the street and raped at knifepoint by a foreign criminal freed from jail after serving a sentence for robbery, yesterday called on Mr Clarke to resign.

Mr Blair telephoned Mr Prescott from his Chequers retreat yesterday to insist that he carry on as Deputy Prime Minister despite the publication of lurid details of his sexual relationship with Ms Temple, 43.

In The Mail on Sunday Ms Temple said that sexual encounters with Mr Prescott, 67, took place in his private office with the door open while a team of seven civil servants worked outside. They also took place in Mr Prescott’s grace-and-favour apartment in Admiralty Arch.

Mr Prescott has said that details of their relationship had been “spiced up” for money and that he will refer The Mail on Sunday to the Press Complaints Commission. The newspaper also reported that Mr Prescott, who has been married to his wife Pauline for 44 years, had a second, two-year relationship with a married former Labour parliamentary candidate at the end of the 1980s.

A Downing Street source said: “Nobody is trying to understate or disguise the serious nature of all this but at the same time he [Prescott] is somebody who works closely with the Prime Minister and is continuing as such.”

A friend of Mr Prescott said: “John is very distressed for Pauline and his family and for the damage he has done to the party. He feels humiliated but Pauline is as keen as he is that he should not resign over this.”

Downing Street also moved to shore up support for Mr Clarke after newspaper reports that Mr Blair was uncertain whether to back him. “Tony still thinks Charles is the man to sort out the Home Office and that nothing that has happened this weekend has changed that position,” said the source.

The febrile atmosphere at Westminster before Thursday’s local elections in England was heightened by the intervention of the head of the public standards watchdog.

Sir Alistair Graham, the chairman of the Standards in Public Life Committee, questioned whether Mr Prescott had broken the ministerial code of conduct which states: “Ministers of the Crown are expected to behave according to the highest standards of constitutional and personal conduct in the performance of their duties.” It will be up to Mr Blair to decide whether Mr Prescott has breached the code.

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