Tears as Brown remembers his baby daughter dying in his arms

"She was unblemished by the illness that she had, " he said. "She just looked beautiful and, er you know. . ."

His voice tailed off and then he added quietly: "She. . . she died in our arms."

Jennifer would have been starting school had she lived, said the Chancellor.

"There is nothing worse than having a young precious baby taken from you, " he said. "And you never come to terms with it. You always know that there's something missing.

"Two weeks ago she would have been going to school for the first time. You know that, but try to do things that make life better so it's had a purpose, so something good can come out of the tragedy."

Mr Brown's voice faltered during the interview with Kay Burley, Sky News anchorwoman, when she asked how he would remember Jennifer.

"We had seven or eight wonderful days, we didn't know she was going to die until the last days, " he said. "So we had very, very happy days.

"It's very tough for any parents faced with a loss that you never expect, that's so surprising, that you have to come to terms with.

"And because you want something good to come of it. . . that's why Sarah and I are interested in what we can do to help other parents in the same position."

It is the first time that Mr Brown has talked at such length about the death of Jennifer.

The Chancellor also revealed how "very lucky" he had been to avoid blindness in his teens. Mr Brown lost one eye playing rugby and owes the sight in the other to an early form of laser technology.

"I was actually very lucky, " he said. "I was able to save the sight in one eye, but not the other."

In the same interview, Mr Brown sought to end the latest bout of Labour feuding by declaring that he would always be friends with Tony Blair. Admitting that they had their "ups and downs", the Chancellor insisted they still had "one of the strongest political relationships in history".

The Brown camp is piling pressure on the Prime Minister in the hope that he will endorse him as his successor at the Labour Party conference in Manchester in two weeks' time.

And yesterday his warm words were endorsed by No 10 .

Asked whether Mr Blair agreed that the two men would always be friends, the Prime Minister's official spokesman replied: "Of course."

Their apparent truce follows weeks of tensions between the pair, culminating last week in an MPs' plot to oust the premier and his promise to quit Downing Street within a year.

In a rare public show of unity, Mr Brown went on: "Tony Blair has been a wonderful leader for the Labour Party and I think over the 23 years I have known Tony, this has been one of the strongest political relationships in history. I think Tony Blair has led the country with a tremendous amount of ability, skill, acumen and sensitivity to what the British people want to see done."

Mr Brown also used the interview to describe Alan Johnson, the Blairite Education Secretary, as a "great friend".

The interview will be seen as an attempt by the Chancellor to promote his personal profile as he prepares to seize the premiership next year.

He said: "I think the public need to know who you are and I think the public need to know where you came from and I think they need to know what shapes the views that you have got. They want to know you are going to be consistent, you are going to be strong, you are going to be someone they can trust."