Last Night's TV - The Hour, BBC2; Britain Through a Lens: the Documentary Film Mob, BBC4

They made the real news of the world

So, here comes The Hour, bent almost double beneath the weight of expectation and specious comparisons to Mad Men. What the latter appears to mean is: (1) They smoke a lot; (2) They wear vintage clothes; (3) There's a good-looking lead who wears a tie. But forget Mad Men because The Hour is its own thing and – on the evidence available so far – a very promising thing too. Abi Morgan's drama about the coming of age of British television journalism has been lucky in its timing, arriving on screen at a moment when the relationship between politicians, the press and the police seems like the only thing worth talking about. But the first episode suggests that it has earned any luck it gets.

The year is 1956, with the Suez Crisis boiling up nicely in the background but getting very little coverage on television news, a bland and reassuring affair modelled on cinema newsreels and easily distracted by society weddings and debutante balls. "Four o'clock. No Eden. No Cairo!" snaps George, the editor, making it clear that his bulletin has no room for international crisis. The person he's snapping at is Freddie Lyon, a self-opinionated Young Turk who is desperate to shake things up. "We are calcifying in television news!" he howls at one point. "We are the nightly reassurance that all is right with the world."

Fortunately for Freddie there is a prospect of a way out – a new current-affairs programme called "The Hour". Unfortunately for Freddie, his friend Bel Rowley has been given the job of producing it, and although she's keen for Freddie to join her on the new team she fears his lack of diplomacy may prevent it. Freddie only has to see a senior BBC executive to explode in a terrifying spume of idealism, ranting wildly about "the mechanics of how we bear witness". He's not even diplomatic with Bel, openly scorning the notion that a woman could be up to the job.

Bel (modelled on the pioneering television journalist Grace Wyndham Goldie) gets this kind of thing a lot. "Such maternal instincts," murmurs Eden's press attaché condescendingly when she makes an inquiry about the prime minister's rumoured ill-health. "I do think you're wasted in news." And the gorgeous Hector Madden (Dominic West at his most lounge-lizardly) clearly believes that his role as the on-screen face of the new programme entitles him to have a crack at an after-hours debriefing of the producer. But, played by Romola Garai as a woman with a core of steely self-regard, Bel looks up to the challenge.

The shabbiness of the surroundings (paint looks as if it's still a luxury) and the sturdily uningratiating nature of the characters are deeply reassuring. As is the casting. Even the smaller roles get fine performances, most notably Jason Watkins as the stultified idiot in charge of making the news as anodyne as possible, Anna Chancellor as a hard-drinking foreign editor and Anton Lesser as a sympathetic BBC news man. A little less certain – so far at least – is whether the thriller component of the drama can match the office politics for texture, or be plausibly integrated into it.

It's a nice touch that Freddie's high-minded contempt for stories about high-society weddings should be rebuked by a story that comes to him through a newly engaged debutante. But you couldn't help wondering, given his prejudices and his passion for social campaigning, whether he'd really take up a lead that was so flaky and David Icke in its delivery. "They are everywhere," his source tells him. "They will kill me if they know I'm talking to you." But if you believe that, you think, why on earth did you go and meet him at the BBC, where "they" could so easily see you? And isn't there something just a little too John Buchan about the cheery cockney newspaper vendor who's on hand with a vital clue? Never mind, once Freddie is on the trail – bunging fivers to friendly coppers here and purloining vital evidence there – a hook of a kind has been fashioned, and the bait of Morgan's script elsewhere is easily good enough to make us swallow it.

Freddie's idealism about the power of the moving image to improve and educate society would probably have had some of its roots in the pioneering film-makers that were the subject of Britain Through a Lens: the Documentary Film Mob, which began with the work of John Grierson at the Empire Marketing Board and concluded with the Crown Film Unit, whose most famous member was Humphrey Jennings. Chris Durlacher's film was an unexpectedly penny-plain history (he's made far more inventive films in the past about Tynan and Orwell), knitting together archive interviews and clips from the documentary footage to explore the odd intersection of propaganda and reportage that flourished in between the war. Grierson, a former street preacher, occupied the Freddie role in this story: "I want to use the cinema as a pulpit," he said, and he smuggled his message about the heroism of the ordinary man into virtually every film he oversaw. Having just watched The Hour, though, I couldn't help but be intrigued by his sister Ruby, who left teaching to work with him and pioneered the most radical development in documentary – letting ordinary people speak directly for themselves, rather than parroting a script written and vetted by civil servants. She died when a ship she was filming on was torpedoed, and you couldn't help but think she might have made history in television too if she hadn't.