Ah, history. How often it turns its heroes into flaw-free paragons of virtue. Until, that is, the Hollywood biopic comes along to redress the balance.

According to Oscar-tipped film Lincoln, however, Abraham Lincoln’s flaw was that he was a bit boring. He also told pointless anecdotes, which everyone pretended were deep and meaningful because, well, he was the president.

The film is set in 1865, as President Lincoln attempts to pass an amendment to abolish slavery. He needs to push it through Congress before the Civil War ends and he can no longer argue that the measure is necessary for peace. So he hires plain-spoken (a euphemism for “sweary”) lawyer W.N. Bilbo to persuade 20 anti-abolition Democrats to vote his way.

Unfortunately, there is so much going on elsewhere (Lincoln family dynamics, general politicking) that the countdown-to-amendment plot gets lost. Even director Steven Spielberg knows this, I think: every so often a character mentions the amendment, presumably as an aide-memoire.

The politics are also problematic. One of the biggest opponents of the amendment is congressman Thaddeus Stevens, who believes it does not go far enough. He wants black people to have the vote, as well as freedom. A key turning point, therefore, involves his backing down: “I do not hold with equality in all things, only with equality before the law,” he repeats over and over. Are we supposed to cheer?

And the film cannot escape the fact that Bilbo and Stevens are great fun, whereas Lincoln is not. They swear. They have funny one-liners (“It opens,” Stevens says, when someone knocks on his door). Lincoln, meanwhile, broods and speaks in aphorisms.

It is a shame, because the film is beautifully shot and well-acted. What it really needs is some streamlining, and some walking and talking in corridors of power. The West Wing with beards and stovepipe hats? Now that would have been a biopic worthy of the Great Emancipator.

Lincoln is in cinemas now.