Britain's likely next prime minister, Gordon Brown, has signed a book deal to write about the nation's unsung heroes, he said on Tuesday, as he bids to soften his image.

'Unsung Heroes' will tell the story of ordinary people whose dedication to a cause has inspired Brown, currently Britain's finance minister.

It is his second book this year — another, entitled 'Courage: Eight Portraits' features essays on figures including Nelson Mandela and Martin Luther King and comes out in Britain in June.

The people featured in the latest book have yet to be announced, but Brown said they were "the kind of heroes we might each aspire to be".

Brown is all but certain to succeed Prime Minister Tony Blair when he leaves office at the end of next month but faces a struggle to charm British voters, many of whom view him as prickly.

A poll last week suggested that Brown is seen as less trustworthy and less in touch than David Cameron, the leader of the main opposition Conservative Party and his likely opponent at the next general election.

Brown has tried to counter such concerns by casting himself as a conviction politician and said last week: "I do not believe politics is about celebrity."

AFP