Let's get one thing straight:
Gordon Brown has not failed.
At least he hasn't failed to get his message across, which is "let the enterprise economy make money and let the centralised state spend it".
And he hasn't failed to put this message into action. The enterprise economy has made money and the centralised state has spent it.
The trouble is that centralised statism doesn't work, and never was going to work. It is an idea that Tony Blair and Gordon Brown made their own and successfully tested to destruction.
That is why Gordon Brown is not a failure. You can't fail without having some sort of chance in the first place. To lose your way you have to have been on the right path to begin with.
New Labour did not fail. New Labour, quite simply, was wrong.