The Weekend's TV: Downton Abbey, Sun, ITV1<br/>The First World War from Above, Sun, BBC1

I love the way historical events leave their mark on Downton Abbey.

Imagine a mud-wrestler coming straight from a bout to rummage through the racks in a bridal shop and you'll have a rough image for the subtle and virtually undetectable way in which world events are interwoven with goings-on at the big house. Take the opening of last night's episode – the last of the current series. Gratefully returning to Downton after the London season, Lord Grantham was anxious to know what the local gossip was. "The main topic here is the murder of the Austrian archduke," said Mr Carson. "Mmmm," replied his Lordship gravely, "I'm afraid we haven't heard the last of that." He was presumably aware, having read the script, that events in Sarajevo were going to crop up about every 20 minutes, just in case the audience forgot what was looming. A little later – justifying the audacious modernity of having a telephone installed – Lord Grantham cited the uncertainty of the times: "None of us know what the next few months will bring," he said sombrely. "Because of the Archduke's death?" replied Carson helpfully, understanding that it's crisis point and everyone must do their bit to mention the war.

This sort of thing is no problem for ironic fans of Downton Abbey, who relish its absurdities almost as much as they do its vicarious wallow in Edwardian grandeur. Given that it has an audience of over eight million people, it presumably must have some unironic fans too, though it's hard to imagine how they preserve their innocence in the teeth of the drama's wild improbabilities. This week, Lady Mary's little faux-pas in bonking a Turkish attaché to death during a Downton house party was still sending out ripples – her sourly envious sister, Edith, having grassed her up to the Turkish ambassador, who clearly felt that he wasn't required to be diplomatic about the shenanigans of the British upper classes. Lady Mary is now looking a little foxed as a marriage prospect ("After four seasons, one is less a debutant than a survivor," says her acidic Aunt Rosamund), though it doesn't seem to have deterred Matthew the Decent from pressing his suit.

Below stairs, Downton Abbey's equivalent of Dastardly and Muttley – Thomas the conniving footman and Miss O'Brien – continued to scheme to get poor, noble, mangled Mr Bates sacked from his position as valet. Sadly for them, even the revelation that Mr Bates had been cashiered for stealing the regimental silver didn't appear to seal the deal – partly because they hadn't taken into account the fact that they are working for the most saintly and forebearing toff in England. He held fire on Bates, convinced there was something a bit odd about his conviction and, rather than dismissing his purblind cook Mrs Patmore, sent her off to London to have her cataracts seen to, dispatching Anna along with her so that she could do a bit of amateur detective work about Mr Bates's past.

Meanwhile, Cora announced that she might be producing an heir after all, a development which threw everything into the air until O'Brien malevolently contrived to have her miscarry, after deploying that unfailingly dependable stratagem – leaving a bit of soap on the bathroom floor. The episode, and series one, concluded with a positive fiesta of solecisms – a chauffeur running hurriedly across the lawns to whisper excitedly in Lady Sybil's ear; a butler giving Lady Mary a consoling hug when he finds her weeping; a footman who is kept on despite being found ferreting around in the butler's wallet and who is then allowed to serve his Lordship's guests with a fresh black eye. Thank goodness for the arrival of a telegram, which drained the colour from Lord Grantham's face and led him to stop the string quartet in mid-bar: "I very much regret to announce that we are at war with Germany," he said. It's funny, but I had a kind of premonition that that might be coming.

Over on BBC, Fergal Keane had actually managed to turn up a fresh perspective on that terrible conflict in The First World War from Above, a programme that featured a recently unearthed French film, shot from an airship just after the end of the war. He'd also gone into the Imperial War Museum archives to look at the thousands of aerial photographs taken by the Royal Flying Corps – images which in some cases provided before and after evidence of the terrible impact of the bombardments. The aerial sections, including what looked like a very white-knuckled flight in a Bristol F2B fighter and a tour of battlefield sites in a modern airship, were freshly instructive about the scale of the destruction and the archive film was extraordinary. But, as is often the case, the details that stuck were those you encountered at ground level and through words – such as one soldier's description of the town of Passchendaele after it had been taken, a place where so many men had died that you could barely put a foot down without "standing on corruption". Keane concluded by visiting the daughter of the French airship pilot – who had eventually been tortured and murdered by the Germans in the Second World War. It seemed like an odd kind of wrong turning at first, a diversion into private biography after an account of cataclysmic history, but her reaction, seeing images that almost miraculously restored her father to a kind of life, was very moving. Her painful emotions stood as a kind of proxy for the millions of losses you'd been hearing about.

t.sutcliffe@independent.co.uk