Parade's End, BBC2, Friday Our War, BBC3, Monday

A starry adaptation of an obscure classic has plenty of horsepower, but is it going anywhere?

With the third season of Downton Abbey coming down the tracks at us, the smouldering wreckage of Upstairs, Downstairs lying in its wake, the BBC could be forgiven for resorting to a proven buffer to head it off. How about the Benedict Cumberbatch double act? It worked quite spectacularly in Sherlock. Here in this adaptation of Ford Madox Ford's Edwardian-era novels Parade's End, Cumberbatch plays – hold on to your homburgs – a Whitehall statistician, Christopher Tietjens, who has a brain like a cut-throat razor. This time round, his down-to-earth factotum is a journalist played by Stephen Graham.

Except – cute joke – almost no one listens to Tietjens when he says things such as "You know you've got a 13-and-a-half-hand harness on a 16-hand horse?". Not exactly Sherlock brain sex, is it? Tietjens is spurned by his political bosses and abandoned by Sylvia, his "Papist bitch" of a philandering wife. Throughout, Cumberbatch is glumly aware of how stuffy Tietjens is, hobbled by his rigid sense of honour: "For a gentleman, there is such a thing as parade, there is such a thing as monogamy and chastity."

Tom Stoppard's script gleefully lobbed zingers such as these in Cumberbatch's direction, and he duly belted them into touch, with that aristocratic thousand-yard stare he has made his own. There were other performances to enjoy. Rebecca Hall plays Sylvia somewhere between Emma Bovary and Made in Chelsea, and Graham is always watchable.

As all this might suggest, Friday's opening episode, the first of five, was happy to let its tone wander. I haven't read Ford's source novels, but I wonder if they're ever quite as slapstick as the scene in which Tietjens's golfing party was raided by suffragettes (one of whom Tietjens falls for). Or as farcical as Sylvia's jaunt to Europe with her lover, her mother and her priest. These sat oddly with a short, moving scene in which Tietjens lulled his young son back to sleep, a boy he's not quite certain is his.

The Great War is on the horizon, and this giddiness, at a guess, was meant to reflect the blissful self-absorption of Edwardian England on the eve of its near obliteration. A leisurely start, then, and one that I hope survives the arrival of the 9pm from Downton sometime next month.

We were left in no doubt as to the reality of military conflict and its shattering effects by the return of the Bafta-winning documentary series Our War. Its producers have gathered and edited thousands of hours of film footage and stills from British soldiers serving in Afghanistan over the past decade, and thanks to the recent advent of the cheap, high-quality helmet camera, serving infantry have been able to record their experiences even as they're engaging the Taliban in the most terrifying firefights.

In Monday's episode, we were invited to follow a company of the Duke of Lancaster's Regiment as it mounted a raid into enemy territory in Helmand to draw fire away from a nearby road reconstruction project. Or as one of the regiment put it ruefully, "give them a bloody nose, and back for tea and medals". If only.

The bald facts are that, back in the summer of 2010 when it took place, Operation Kick the Hornet's Nest managed to "engage" the Taliban for three days, sustaining two fatalities, Captain Andrew Griffiths (IED), and Kingsman Darren Deady (shot). A tense narration and some unobtrusive graphics joined the logistical dots. The recollections too were moving, tinged with tears, some dark humour and typical military euphemism. ("It was perhaps a little more kinetic than we had expected.") Griffiths's father – a brigadier in the same regiment – and the young Deady's mother spoke tenderly about their vain hopes that their wounded children, evacuated back to the UK, would survive.

But what hit home was the contrast between these reflections and the stomach-churning reality in the footage of the men, screaming on farmhouse rooftops as they fired at an enemy we never saw, and then desperately trying to save their wounded comrades − and all edited into a hellishly compelling narrative. "Kinetic" is one word for it.

This was presented to us without any context wider than the soldiers' own experiences. But these were so disturbingly vivid in this remarkable programme that the issue of whether the British military should still be involved in Afghanistan was left ringing in the air, the great unanswered question.