An unfortunate side-effect of ITV’s prolonged period of corporate and creative woe has been that when the network does actually put out the odd programme of genuine worth, it tends to get lost in the wash. A striking example was this year’s See No Evil, which, when it was broadcast in spring, generated a few headlines thanks to its subject – the Moors Murders – but not nearly enough about its brilliance as a piece of television.

Rare though it is, when something like See No Evil comes along you realise TV’s primacy – over movies, newspapers and even, still, just about, the internet – in having a direct line to the British psyche. There has been a plethora of true-crime dramatisations in recent years, and it took no time for 9/11 shows to start appearing; yet, four decades after Pauline Reade’s murder, a drama based on the crimes of Ian Brady and Myra Hindley still seems singularly taboo. The triumph of See No Evil was taking care to respect that, yet not be crushed by it. It carefully avoided sensationalism, but not at the expense of searing, probing drama, and bleak moorland scenes of a resonant, almost primal power.

It’s curious enough that, after such a long moratorium, two Moors Murders dramas should show up within five months; what were the odds that both would turn out to be seriously good? Longford, which explores the relationship between the prison reformer Lord Longford and Myra Hindley – for whose parole the former cabinet minister campaigned tirelessly, fruitlessly and thanklessly over the final three decades of his life– is a very different drama, made by different people for different reasons, but, inadvertently, it is also the perfect sequel to the earlier film.

Played by Jim Broadbent, Lord Longford himself is, as the title would suggest, the focus. Five years on from his death, the man born Frank Pakenham in 1905 is in the process of becoming a forgotten figure, remembered, when he is remembered at all, as a wispy figure of fun, a well-meaning fool, thanks to his bewildered twilight campaigns against pornography in the 1970s, and especially his controversial championing of Hindley’s cause.

Written by Peter Morgan, however, the new film goes deep behind that fading public image to the solid core of the man. Morgan, who wrote The Deal and its semi-sequel The Queen as well as the play Frost/ Nixon, is obviously a writer who values research, but he is not a writer who will allow it to constrain him. As with all docudramas, characters, events and dialogue are melded, changed and outright invented; but where Morgan stands out is in how he manages to discover a plausible, water-tight emotional truth. You might not see what really happened exactly how it happened, but it sure feels like you do.

A deeply religious man, Longford started his weekly visits to prisoners in jail in the mid-1930s, and carried on until he was in his 90s. His fundamental conviction was that, as Broadbent says in the film, “no human being is beyond forgiveness.”

That’s an easy platitude to mouth, but a complicated code to live by and, if you go about trying to practice it to the letter, as Longford did, with an almost otherworldly certitude, opprobrium and scorn seem to be the best you can hope for. But rather than the derision and anger his sympathy for her provoked, it was Hindley herself who presented his faith with its biggest test, by using and betraying his compassion. Add to the mix the fact that Longford also visited Ian Brady and you have an irresistible set up for a dramatist – an authentically good man, going down to meet evil, with only faith as his shield.

Broadbent offers a quite uncanny portrayal of Longford. Astonishingly, for such a beloved and familiar actor, you forget who it is you’re watching. Broadbent disappears the way Alec Guinness once did. He is matched at every turn by Samantha Morton, who has one of the hardest tasks of her remarkable career as Hindley. Her portrayal is markedly different to Maxine Peake’s unsettling, brassy hot-cold blast in See No Evil. (Although there are some subtle similarities.) Post-peroxide, Morton’s Hindley is smaller, more nondescript, more sympathetic. But you slowly realise she is not playing Hindley: she’s playing the Hindley Longford wanted to see, which is perhaps who Hindley was playing herself.

There’s a fine cast – Andy Serkis, who must have thought his characters could only go up after Gollum, is an unsettling Brady, and Lindsay Duncan is superb as Longford’s wife. But the heart of the film is of course the meetings between Longford and Hindely. Broadbent’s eyes, you notice for the first time here, are of a striking, open, Paul-Newman-rivalling blue; across the prison table from him, Morton’s are unreadable, dead pools, with fleeting glimpses of something churning deep down in there.

Ultimately, though, the real relationship under scrutiny is not Longford’s with Hindley, but our own relationship with his views – “no human being is beyond forgiveness” – and the challenge that he and his views continue to pose us all.

Published in The Sunday Herald, October 22 2006