Oliver Stone has called his apparently well-researched but essentially fictional biography of George W Bush “a Shakespearean tragedy” — even though it ends long before the ascent of Barack Obama to the Presidency and the rather Lear-like end-game that will be played out by a toothless Republican administration for the next 70 days.

The essential reason is that Stone feels Bush Junior could never fully satisfy his patrician martinet of a father, whose one-term Presidency committed America to the first Gulf War but not the continuing mess of the second invasion.

Shakespearean? It is hardly that. There are many moments which don’t gel with one’s own memories of Dubya’s first term as president — but W is still a great deal better than some have said, and worthy of comparison with JFK and Nixon, Stone’s two other essays in imagined history.

Its chief virtue, apart from the acting ability of the excellent Josh Brolin as Bush and a pretty good cast, is that it strives mightily to be fair, despite the fact that Stone regards the strange Texan at its centre as the worst President since the war (Truman, amazingly, is second and Nixon third).

He does not seek to portray Bush as a bad man but rather a natural neo-con whose mistakes led his country into three unwinnable wars: Iraq, Afghanistan and, worst of all, the war on terror.
We see Bush and his kitchen cabinet discussing at length what to call his foreign enemies and finally deciding on the “axis of evil”, despite General Powell’s opposition to putting Iran, Iraq and North Korea into the same box. We also see how, once his limited mind is made up, an innate stubbornness kicks in which nothing will dislodge.

He is furious that no one told him earlier that Saddam had no weapons of mass destruction, and so was unwittingly bluffing in front of his own people, believing America would never invade.
But his real and continuing worry during his presidency is what Bush Senior, beautifully played by James Cromwell, thinks of him. The reason behind this is that he was a failure at everything he did up to the age of 40, thus shaming himself and besmirching the Bush dynasty.
Even when he gives up drink in a not very convincing sequence, gets God (in a better one, via the agency of Stacy Keach’s evangelist pastor) and manages to push his way to the top, he never believes his father has come round to him.

All this is feasible, but it’s clearly not the whole story. The present scenes in America remind us that real facts can be stranger than anybody’s fiction, and in this case the whole truth might have seemed less credible.

Stone starts his story with the young Bush at Yale, where he is tormented in one of those appalling freshmen inductions, loses a local election to a good ole boy Democrat, tries a variety of jobs badly, courts his librarian wife (who incidentally once voted for Lyndon Johnson) and is then persuaded to take up politics more seriously.

The tale ends just before 9/11, as the anti-war movement gathers pace and Saddam’s weapons of mass destruction seem a figment of American and British imaginations. We see him, in an unwise piece of magic realism, on the field of his favourite sport (baseball) trying to catch a high ball which never comes down into his gloves.

What we don’t see is the reaction to 9/11, to the New Orleans hurricane mess and to the credit crunch which destroyed his economic policy at a stroke. That is surely another film — one day it might be mounted, by someone other than Stone.
Some of the performances are more convincing than others, though nobody should expect more than (often effective) nods to the physical attributes of those we have come to know so well.

We have Toby Jones as a wily Karl Rove, Jeffrey Wright as Powell, Scott Glenn as Rumsfeld, Richard Dreyfuss as Dick Cheney and Thandie Newton as Condoleezza Rice. It is not Martin Sheen as Tony Blair but Ioan Gruffud in a rather gentle and brief cameo, while Ellen Burstyn and Elizabeth Banks are Barbara and Laura Bush.

All these are able performances, though Newton is asked to be a rather creepy approximation of Condi, whom most of us would probably consider one of the more intelligent and liberal of the odd group around their master.

Brolin, of course, is on screen most of the time and manages to make Bush less of a figure of cartoonists’ fun than one might have expected. His Bush is more of an ordinary Texan politician, a man who bravely overcame his early demons and came to believe implicitly in his destiny as the world’s most powerful man.

Clearly there are many other ways of making a film about Dubya. But Stone’s version should at least be respected. It may be only half the story but that half contains enough to make us think, and keep on thinking how the hell it all happened.