Tony Blair’s A Journey is now the fastest-selling autobiography ever, up there in the bestselling league with Dan Brown and JK Rowling. The British Legion, and the people it serves, will benefit from Blair’s generous endowment for many years to come. The publishers were worried Mandelson’s memoir would spoil sales – they needn’t have worried. Mandelson may be a Prince, but there’s only one King.

I got my copy an hour after it hit the bookshops, in Waterstone’s in Eastbourne. I was the first person to buy one. There was no queue. Have I read it? Well, yes and no. I’ve read the parts that the media thought interesting: the descriptions of the corrosive relationship with Gordon Brown (whom Blair blames squarely for personally organising the ‘curry house coup’ which brought him down), the weird ‘premonition’ that John Smith would die and Blair would become leader, the political development of the Labour government, and the Iraq war, the admission of drinking too much booze (gin and tonic, for heaven’s sake).

I’ve read the sections about issues or events where I had a walk-on, non-speaking role: the rewriting of Clause IV, the election campaigns, and the health service reforms. Progress gets an almighty telling off on pages 620-621 for going all soft at the moment of transition from Blair to Brown. Naughty Progress.

I’ve looked in the index for people I know and like, and read what Blair thinks about them. You have to feel a little sorry for Phil Collins, Blair’s speechwriter, who appears in the index, but not on the page – a victim of some last-minute edit, no doubt.

I’m afraid the section on Northern Ireland is a pleasure that still awaits.

The prose style is a curious combination of religiosity and the kind of slack vernacular that I would tell my son off for using. The religiosity comes from both the Biblical language which appears throughout, and from the confidence of the political assertions. The lapses into slang are at times hilarious (‘wet our knickers’, ‘wuss’). Running throughout the book, though, is a political analysis and conviction which bears closer examination. The book is selling in huge numbers because of its breathless pace and readability. But for progressives, it is worth reading for the politics.

‘Blairite’ is one of those lazy terms which has no meaning. It can be used to denote anyone who worked closely with Tony Blair himself, which meant most of the cabinet, ministers and advisers. ‘Blairites’ just meant a supporter of Tony Blair. In 1996 I was interviewed on BBC Newsnight, and described on air as a ‘Blairite’. Later, my mum asked me how the play was coming on. What play? Oh, on the TV they called you a ‘playwright’. For critics, it can be used as a term of abuse. It has peppered the leadership contest. Many political leaders have attracted a following of -ites: Bevan, Gaitskell, Kinnock, Thatcher, Brown. Few can claim an -ism. There are Brownites, but there isn’t a Brownism. The personal clique is not bound by a common philosophy, just tribalism and self-interest.

So is there a Blairism? The book contains enough material to suggest a canon of political belief which adds up to a coherent weltanschauung. A belief in the innate worth of human beings; liberal democracy as the best way to organise states; the understanding of globalisation as the dominant feature of our age, and the necessity for political and economic institutions and cultures to adapt to it; the responsibility of democracies to intervene into failed and rogue states which threaten their own people or regions; the limits of the central state as a tool of social progress or economic prosperity. The disregard for tradition, where it drags back progress and advancement. These themes transcend Blair’s individual policy foibles, such as his contempt for the freedom of information act or the ‘ban’ on fox-hunting.

It’s not helpful to credit an individual with an entire political creed. It fuses the political with the personal, and allows the first to be discredited by the second. We can leave that to the Marxists. Blairism for me stands today for what it stood for in the early-1990s – a laudable attempt to apply democratic socialist values to a fast-changing society and economy, with the vital insight that policies are a tool, not an end in themselves. Historically, this is called revisionism. It can be traced back to Eduard Bernstein attempts to revise Marx, via Evan Durbin in the 1940s, Crosland in the 1950s and 1960s, and Kinnock in the 1980s. Revisionism is a political method and approach which allows Labour to be truly the party of modernisation – always anticipating the next issue or cause, not held down under the weight of outdated policies. In the future, it may get dubbed ‘Milibandism’, although I hope we can avoid such ugliness. But it remains the best and only methodology which guarantees Labour’s continuing relevance, and capacity to change society.

The new leader should read the book, not just the bits where they get a mention, and recognise an important truth: modernisation is the only game in town. Labour is either the party of modernisation, or it will become a party of protest and opposition. Winning or whinging – that’s the choice on the next stage of our journey.

Paul Richards is author of Tony Blair: In His Own Words. His latest book Labour’s Revival is published at the end of this month.