Restless, BBC1, Thursday and Friday / The Girl, BBC2, Boxing Day / Downton Abbey, ITV, Christmas Day

Hayley Atwell's on a suicide mission in a tense spy drama; she must match Charlotte Rampling

Had you awoken, slumped before the box, from a post-prandial carb coma on Thursday night, you'd have been forgiven for thinking that the makers of Downton Abbey had really lost it this time.

There was Lady Mary Crawley, sanguine and patrician as ever, dressed in 1970s cheesecloth and denim, nonchalantly dragging on a roll-up cigarette. A Quantum Leap or a Dallas-style dream sequence? Happily, Michelle Dockery was just taking a break from the Abbey to put in a turn in the BBC's pretty satisfying adaptation of William Boyd's bestselling thriller Restless.

Dockery plays Ruth, a young mother plunged into a world of vintage espionage when her mother, Sally (played by Charlotte Rampling), confesses that her name was once Eva Delectorskaya and she had been a British agent during the Second World War. Forced to disappear in fear for her life, Eva is convinced her enemies have finally caught up with her and enlists Ruth to unpick a web of intrigue going back decades.

Flicking between past and present, Restless – adapted by the novelist himself – is a high-quality, pacy watch, despite a strange disjunction between the two halves in the TV version. This is, I think, due to casting – Hayley Atwell makes a passable young Eva, but Rampling could out-act anyone with one eyelid. She brings more tension to unpacking groceries in her chocolate-box cottage than Atwell can summon while pointing a gun. Less than wholly credible either was that Rufus Sewell, as spymaster and love interest, would end up as Michael Gambon. Ageing is cruel, I know, but even so ....

It was “spot the redeployed Downton star” again on BBC2, where Mrs Crawley (Penelope Wilton) popped up as long-suffering PA to Alfred Hitchcock (Toby Jones) in the BBC/HBO biopic The Girl. Billed as a study of the relationship between the British filmmaker and the actress Tippi Hedren, Sienna Miller starred as the model transformed into an icy blonde screen icon thanks to The Birds and Marnie.

That this was not an easy metamorphosis is well-known. Hedren has spoken of being the object of a pernicious obsession and it's certain that the pair eventually reached a stand-off, Hitch keeping Hedren under contract, preventing her taking any other roles though never working with her again. The infamous scene in The Birds in which Hedren is beset by an angry flock of live creatures, sprung on her after having been assured by Hitchcock that they would be using mechanical facsimiles – has been taken as evidence of the director's sadistic impulse towards his heroine.

So, although The Girl was a seductive visual affair – feeding madly off Miller's beauty – what it needed was new insights, recasting the light and shade of familiar scenes from the films. The male artist who reifies his female muse is a narrative as old as art itself. Ditto that of the bothersome boss and comely young employee. What begged to be untangled was the coincidence of unhealthy personal relationships and creative chemistry too often formulated as cause and effect.

Here, Jones's Hitchcock was a pathetic figure – a podgy, heavy-breathing teller of dirty jokes, shuffling charmlessly after a Hedren who was almost as blank as the on-screen cipher the actress claimed to be afraid of becoming. Perhaps the truth really was this dull and unedifying, but the films that resulted offer a far darker version of that relationship that just made The Girl feel rather pale and pointless.

And so to the full complement of Downton Abbey cast in, well, Downton Abbey. It was the Christmas special, but quite honestly this year's Queen's Speech had more suspense. Chief plot points (spoiler alert) to squirrel away for the next series are that Lady Mary had a baby boy, or rather an heir, so celebrations all round. The bad news is that while Matthew was motoring back from the hospital, the scriptwriters realised that nothing had happened in the last hour and a half, so conjured up a massive crash. Blood coming out of the ear is not a good sign – although Matthew has had at least half his body resurrected in the past, so we can only wait and see.