There are 5 words one doesn’t want to see at the start of a film – ‘based on a true story.’ The dead hand of truth and real life can grab a film by the throat and stifle the life from it; truth in real life is vital, truth in art less so.

Denial suffers from this throttling grip: it’s worthy and sincere and believes in itself and tells an important story clearly and well. It’s engaging, well-acted, means well, it’s nicely filmed, decently lit, there are no glaring plot-holes or continuity bungles, the music is pleasant with judicious use of Schubert, it hangs together – if it sounds like I’m struggling, I am because it lacks the spark of passion that would make it great.

The plot (not really plot) is straight-forward and swiftly outlined. Well-known Holocaust denier and racist ‘historian’ David Irving sues Deborah Lipstadt (an American academic) and Penguin Books (her publisher) for libel after she accused him in one of her books and the film tells the story of the subsequent court case. And, er…that’s it. There is no sub-plot; no love story, no sex. Irving chose to sue in the British courts which gives an excuse for this American film to dissect the vagaries of the British legal system for an American audience (e.g. the separation between the roles of solicitor and barrister), as well as find roles for the usual British thespian suspects.

I’ve seen photos of Deborah Lipstadt and she looks like what she is – an academic –  pleasant, sincere, clearly highly intelligent but she doesn’t live by nor trade on her looks; she doesn’t need to. Here, she’s played by Rachel Weisz, an attractive, serious actress approaching that difficult time in her career when Hollywood starts to lose interest in women of a certain age. Now I’m not saying that beautiful women can’t be intelligent, or vice versa, far from it, but there’s something about the cold cynicism of her casting which made me not fully believe in her.

Tom Wilkinson as her barrister is, as usual, excellent. Timothy Spall as David Irving is convincing and odd at the same time – there’s a strong resemblance but he puts on a too-studied strangulated, nasal posh accent which makes him sound exactly like James Fox in Day of the Jackal; but all you keep thinking is – hasn’t he lost weight? John Sessions (where’s he been?) has a small role as a Cambridge historian, as does Mark Gatiss as a German historian and Alex Jennings appears as the learned Judge. Harriet Walter plays a concentration camp survivor and does her best but … can I say she’s straight out of central casting without that making me sound completely cold and dead inside?

There is a very moving scene shot at a cold and mist-shrouded Auschwitz (although oddly there are no other tourists there) but there are a few too many scenes of fusty lawyers drinking wine in Lincoln’s Inn Fields’ musty offices surrounded by dusty books and Oxford educated paralegals and interns.

But…it’s worth seeing as a decent, almost good film, it reminds you of something that we should never be allowed to forget and there’s a happy ending – Irving loses the case and is exposed for all the world to see as a liar, charlatan and holocaust denier; although oddly it then shows him being interviewed by Jeremy Paxman on Newsnight where he continues to espouse his hateful beliefs.  It’s just a shame that the film never really sings – it lightens and gladdens the heart but still leaves one a little unmoved. The actors do their best to ‘act’ passion but you never quite lose the feeling that they are acting.

In these Trumpian times of alternative facts where worthless opinions are touted as truth and nonsense spreads over social media like a cold mist, this is a timely reminder that there are ways in which nonsense and lies can be countered and defeated. However, one suspects that those who ought to see it, won’t and those that see it already know the truth of the holocaust. One wonders how it’s gone down in the Donald’s White House