When Gordon Brown launches his bid for the Labour leadership in London on Friday, it will mark not just a new era but an epiphany for the 56-year-old chancellor. For the first time in nearly 15 years, he will appear before the British public as a figure in his own right, a politician finally unbound and able to set out his own vision for Britain.

Throughout Labour’s decade in power, Mr Brown has been a chancellor of rare power and reach – in many ways the most remarkable of modern times. But throughout it all, he has never truly felt himself master of the political scene. Ever since he stood aside to allow Tony Blair a clear run at the Labour leadership in 1994, Mr Brown has stood in the prime minister’s shadow. Almost every public utterance has been scrutinised for what it reveals about the creative, yet tortuous, political relationship between the two men.