HOME Secretary David Blunkett sacrificed his political career last night to pursue his paternity claim to his ex-lover Kimberly Quinn's son.He was swiftly replaced by another celebrated Cabinet bruiser Charles Clarke – MP for Norwich South – whose job as Education Secretary was taken by Cabinet Office minister Ruth Kelly.

HOME Secretary David Blunkett sacrificed his political career last night to pursue his paternity claim to his ex-lover Kimberly Quinn's son.

He was swiftly replaced by another celebrated Cabinet bruiser Charles Clarke – MP for Norwich South – whose job as Education Secretary was taken by Cabinet Office minister Ruth Kelly.

Mr Blunkett's relationship with Mrs Quinn proved his inevitable undoing after finally admitting his office had been involved in "fast-tracking" her Filipina nanny Leoncia Casalme's application for leave to stay in the UK.

Mr Blunkett defended himself by insisting he felt he had not been involved personally in any wrongdoing.

Mr Blunkett's resignation became inevitable during yesterday as members of the Cabinet and senior Labour backbenchers made clear their patience with his personal problems had been tested enough.

The end came as the Home Secretary issued a statement through the Press Association just after 6pm saying: "When the issue of the application for ILR (indefinite leave to remain) for Ms Casalme emerged on November 28, I immediately asked for an inquiry to be set up. Sir Alan Budd has undertaken that inquiry over the last two weeks.

"The key issue has always been whether I used my public office for private benefit.

"Since these issues were first raised, I have always given my honest recollection of the facts, on the record as I remembered them.

"At that time and subsequently I said that the issue of Ms Casalme's application was not taken up by my office beyond it being read to me initially. These statements have been based on the recollections of myself and the officials in my office at the time.

"Yesterday, Sir Alan Budd told me there had indeed been a fax and an exchange of e-mails between my office and the Immigration and Nationality Directorate – not based on the application form as originally alleged but on the subsequent letter (informing her of a possible 12-month delay) of which I was always aware but did not remember holding a copy. I have no recollection of dealing with this in any way.

"However, whether or not I asked for any action to be taken is irrelevant to the inference that can be drawn.

"Given I have no recollection of issuing instructions to deal with the application, but only to continuing the elimination of the backlog in general, the easy thing would be to hide behind my officials. I will not do such a thing. In no way is my office or any individual within the department to blame for what happened.

"I have always been honest about my recollection of events. But any perception of this application being speeded up requires me to take responsibility.

"That is why with enormous regret I have tendered my resignation to the Prime Minister today."

In his resignation letter to Mr Blair, Mr Blunkett said: "In making my decision we have carefully considered the damage my seeking to remain in office may cause to the Government.

"It would be more than I could bear if allegations which have arisen because of my private life were to overshadow the very real achievements of this Government and this department."

Mr Blair replied in a letter, saying: "It is with great regret that I have accepted your resignation from the Government this afternoon.

"You have been a truly outstanding Cabinet Minister as both Home Secretary and Secretary of State for Education and Employment. You have made real and lasting change to Britain.

"You leave Government with your integrity intact and your achievements acknowledged by all. You are a force for good in British politics."

The Home Secretary made no secret of the emotional turmoil involved in his departure when he toured the TV studios. "If I was ever going to see my youngest son again, if I was ever going to hold him as I did as a baby in my arms, there were going to be consequences.

"I hadn't fully grasped the enormity of those consequences. But in time people will understand what I have been through, what I am prepared to go through, what I was prepared to sacrifice along with my three elder sons for that little boy."