Gordon Brown has insisted that Tony Blair is his friend, and always will be, despite Labour's recent squabbles.
Countless stories have been written about their relationship
In a television interview with Sky the chancellor admitted their friendship has had its "ups and downs".
But he says it is still one of the strongest political relationships in history, despite reports they fell out.
The interview came as the Cabinet met for the first time since turmoil erupted over Labour's leadership. Mr Brown denies plotting against the PM.
Trade and Industry Secretary Alistair Darling said Thursday's Cabinet meeting was "businesslike", dealing with issues like the Middle East and Afghanistan, as well as domestic affairs.
"All of us are very determined that we get on with the business of government," Mr Darling told BBC News 24.
Asked if the meeting had been friendly, Mr Darling replied: "Absolutely. We're always very friendly."
'Ups and downs'
Reports claimed Mr Blair and Mr Brown had a huge row a week ago when discussing the timetable for the prime minister to step down.
Some observers say the two men's rivalry has become bitter over the years.
In an interview being broadcast on Sky News Lunchtime Live, Mr Brown was asked if Mr Blair was his friend.
The chancellor replied: "Yes, and he will always be my friend. And you build friendships, but friendships have ups and downs as well."
'Skill and sensitivity'
He added: "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."
He dismissed questions about whether the two men had done a deal in 1994, in which Mr Brown agreed not to contest the leadership as long as Mr Blair would pass it to him later.
And he hailed Mr Blair's achievements, listing Northern Ireland, hospitals and schools, high employment and economic stability as highlights.
The prime minister's official spokesman was later asked if Mr Blair shared the view that he would always be friends with Mr Brown.
"Of course," he replied.
Education Secretary Alan Johnson, who is seen as a potential leadership challenger to Mr Brown, is giving a speech in Exeter on Thursday.
Mr Brown was asked if he would like Mr Johnson as his deputy leader.
He replied: "Alan's a good friend, one of many friends, but politics isn't about personality."
Mr Brown said he would like written on his tombstone: "He tried to serve people."
The chancellor said his vision was that Britain could probably become the most successful country in the coming decades, with a strong economy and cohesive society.
But he warned: "There is no doubt that there is a second generation of al-Qaeda terrorists.
"There is no doubt that after September 11 there is still a new generation of terrorists coming along.
"We have got to fight them militarily, we have got to fight them by our intelligence services, and I have provided more resources than ever before, and then we have also got to win the battle of hearts and minds."
Mr Brown also told about his feelings about his daughter Jennifer Jane, who died aged 10 days after being born prematurely in 2002.
"You always know that there's something missing," he said.
"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."
He said that losing a child unexpectedly was "very tough for any parent".