Former Cabinet minister Peter Mandelson has condemned as "too timid" Labour's first five years in power, in which "real delivery proved patchy".
The Hartlepool MP, who was one of the chief architects of New Labour, also attacks the Government over the use of "spin".
Its character has been harmed, he says, by letting spin "fall into disrepute through overuse, and misuse when in experienced or over-zealous hands".
Mr Mandelson's comments are published in an updated version of his new book, The Blair Revolution - serialised in the Guardian newspaper.
He says that while the Government's achievements had been considerable, it was still failing to achieve the goals of social democracy because too often it had "just tinkered".
New Labour had seen many of its strengths being turned into weaknesses. In the years following its 1997 General Election victory, "real delivery proved patchy" leading to a lack of public engagement with the Government.
He says the "weakness" had been particularly evident at the level of the local community.
"For all the action zones, new deals, and strategic partnerships that have sprouted since 1997, too many of the worst estates and deprived communities remain unchanged - bleak ghettos depressing the spirits of all who live in them, dominated by the fear of crime and racial tension, too often becoming centres of danger and desperation," he says.
"New Labour has talked a good game, including obligatory denunciations of snobbery, racial prejudice, the closed shops of the professions and restricted access to universit-ies and the civil service," he says.
"But has it really taken these citadels by storm and made a difference for the sort of young people who live in my constituency and feel shut out because so many paths are barred to them? The answer is no. We have just tinkered."
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