Lord Mandelson has said he is comfortable with his portrayal of Labour’s years in power and the relationship between Tony Blair and Gordon Brown.

The peer launched his memoirs The Third Man last week and has been criticised by some Labour figures for the detail of the book.

Labour leadership frontrunner David Miliband called it destructive, while his brother and rival for the post Ed Miliband said it “offended just about everyone”.

The book describes the fractious and awkward relationship between Mr Blair and Mr Brown, although some Labour critics have attacked him for “damaging” the party’s chances of regaining power.

Speaking on BBC1’s Andrew Marr Show yesterday, Lord Mandelson countered that he had written the book for the general voting public, rather than for those inside Westminster.

He said that if he had not given an honest account, he would be “sitting here a lot less comfortably than I am”.

Lord Mandelson said: “I know for some people inside the Westminster village it will have come, dropped like a sort of rather controversial explosive bombshell. But you know I didn’t write this book for people inside the beltway – I wrote it for the general voting public.

“And I knew right from the beginning that it had to be honest and it had to offer a compelling, well-written story.”

Lord Mandelson said last week he was “proud” to have blazed a trail for out gay politicians to succeed regardless of their sexuality.

He told The Times: “I think it’s important that people should be able to get to the top of politics – or whatever profession they aspire to travel to the top of – irrespective of what they are.

However, critics have pointed out that his dog gets more mentions in the book than his partner does.