Speaking at the Hay Festival in Mid Wales, where he was promoting a new book on his political heroes, Mr Brown admitted: "It's clearly divided the country."

He urged people to "be fair" to Tony Blair over his 10-year premiership and spoke of the Prime Minister's "enduring achievement".

Family formed a core part of his wide-ranging discussion in front of a 1,200 capacity audience.

Proceeds from the book, Courage, are going to the Jennifer Brown Foundation, set up by the Chancellor and his wife after the death of their daughter. He spoke emotionally of the profound effect she had had on his life.

He said: "It made me believe that every single child matters. Every single child deserves our best endeavours and deserves our support to help them make the most of their potential.

"If I was taught something by the experience it is that every child is precious. We have a duty as a society for every child to make the best of themselves. It is an absolute duty. It's not something we can walk away from."

Talking to interviewer Mariella Frostrup, a casually-dressed Mr Brown appeared relaxed. He cracked jokes with the audience but at times struggled to be heard above the torrential rain inside the marquee.

The audience was given a glimpse into the kind of prime minister Mr Brown will be during the event.

He said his vision was for "all countries and all continents" to work together to a common aim. Mr Brown also promised a new form of government when he becomes prime minister later this year, and said that public consultation will be an important part of that.