A dozen years have passed since Downton Abbey first landed on our TV screens, since when it has passed into folklore. Whether you thought it was escapist historical froth, a ludicrous anachronism full of class-system clichés or a documentary probing the British aristocracy, Downton has lodged itself in the national consciousness, probably forever.

The prolific Lord Fellowes returns with this six-part adaptation of his own novel (for ITV), a niftily-wrought yarn (originally issued in online instalments) about the old aristocracy and the rise of new money in the early 19th Century. Some are inevitably calling it the “new Downton”, but it really isn’t.

Crooked House is being released as a film in various territories, but has already been shown on television in America and has now surfaced as a drama on Channel 5 bearing the title Agatha Christie’s Crooked House. It duly falls in with a recent televisual tradition for serving up the Queen of Crime as a Christmas treat.

Hope Dickson Leach’s debut dissects lives in a wintry English landscape. The catastrophic 2014 floods in the Somerset Levels are the background to the return of Clover (Game of Thrones’ Ellie Kendrick) to a farmyard home which simmers with unspoken secrets.

From the schoolroom straight to the throne: it was a rapid rise for 18-year-old Victoria, and managing as monarch wasn’t helped when everyone around you had their own agenda and was raring to act on your behalf. Moving nicely from TARDIS to palace – and mercifully from Alexandrina (even worse as the shorter 'Drina) to Victoria – Jenna Coleman in the title role combined wide-eyed innocence with an independence and hints at a steelier impetuosity that delivered well in this opening episode (of eight) of what has already been dubbed the new Downton.

If one was going to write the recipe for a classic British children’s film, it would probably include the following: adapt much-loved novel; hire fresh-faced young actors and well-worn comedians; budget for steam trains chugging over viaducts; ensure messing around in boats; add lashings of pop and sprinkle with a faint whiff of jeopardy.

“Murder is hilarious,” quips Zawe Ashton’s scheming maid, and in Jamie Lloyd’s high-octane, queasily comic revival of Jean Genet’s radical 1947 play, it really is. It’s also lurid, strange, bleak and powerfully transcendent, as befits a piece that locates hunger for creation and liberation in the imitation and destruction of another.

On Monday ITV showed BAFTA Celebrates Downton Abbey, in which a massed gathering of cast and crew plus a few celebrity guests toasted Downton's five-year stampede to global acclaim. Its creator Julian Fellowes waddled onstage and told an anecdote about how he'd been accosted by a Downton fan while browsing in a Barnes & Noble bookshop in New York. "Just let Edith be happy!" she wailed at him.

They said there'd never be an audience for a period drama about an aristocratic Edwardian family. Six series later, we're bidding adieu to a national (and indeed global) institution, as Julian Fellowes's motley band of ridiculous, ahistorical and frequently exasperating characters potter off into the fading TV sunset. There's still the Christmas special, but – though we might not admit it – we'll miss them.

Maggie Smith rarely gives interviews. In the week that Downton Abbey's last-ever series episode is broadcast, and she reprises on screen her role in Alan Bennett's The Lady in the Van (pictured below with Alex Jennings), theartsdesk revisits an encounter that took place in Highclere Castle in 2010. It was the only interview Dame Maggie gave that summer apart from one – which took place just before – to Julian Fellowes.