Downton Abbey never fails to over-promise and under-deliver. There is, at least, a kind of consistency in this; but it makes for exasperating viewing.

After the calamitous events of last Christmas’s festive episode, this year, writer Julian Fellowes was taking no chances. Like an over-cautious Christmas tree decorator, he sought to take his characters out of the box, play with them a little, and then return them to exactly the same condition as when he first found them.

True, Ivy finally got an exit after a couple of series of underwhelming storylines and there was the rosy glow of flirtation between Carson and Mrs Hughes; but, in a series that prides itself on reminding us every week that a new world order is coming, it was, as so often, the case that nothing really changed.

Writing that is this plodding will always have its greatest friend in exposition and here the episode did not disappoint, giving to Ivy in the opening moments the observation that Lady Edith had returned from eight months in Switzerland looking more tired than when she went. Thus the dramatic potential of Edith’s pregnancy storyline was immediately done away with. All the screen time that Edith had spent finessing a Swiss future for her child was undone: the child would be raised, as she had first planned, by a tenant farmer on the estate.

But neither Edith’s daughter, nor the revelation that the child’s father had been coshed over the head in Berlin, was the main event here. The bigger news was that Rose – having turned her attention from Jack Ross to Ambrose and his orchestra – was coming out, thus the Downton massive would get to rub shoulders with royalty!

Cue guest appearances from Shirley Maclaine and Paul Giamatti: the former of whose job it was, as ever, to proclaim a future for tawdry, progressive America in the face of so much old world complacency. Espousing the cause of a new world where servants might be free to comment on the canapés was Harold’s valet Ethan Slade – as perkily effete a man as ever showed an interest in Daisy, but she seemed to miss the obvious inference and had her head genuinely turned for all of five minutes. One-nil to the New World, then.

Unfortunately, that the Old World didn’t much care for such radical salesman patter was shown by the sudden outbreak of Frenchitis that gripped the Crawley clan, clearly keener to hold onto pre-revolutionary ideas of aristocracy. Isobel was confessedly ‘sérieuse’, the Dowager Countess a metaphorical sister of Marie Aintonette with a disdain for the ‘déjeuner de soleil’, and even Lady Mary made the assumption that Charles Blake was a would-be Robespierre. He wasn’t, as it turned out, being heir to a hitherto-unmentioned Ulster estate, so Lady Mary is now free to fancy him without the need for any more pigs to act as unlikely go-betweens.

Typically, Mrs Hughes was more stout-sensed than to fall for any of this Francophilia, but then, she has always shown more in common with the Belgians, being Downton’s very own Hercule Poirot, and thus her little grey cells were exercised on the not-so-small matter of Bates’s coat.

If only Bates, like Sampson, had had his eyes fixed on Lady Rose’s handbag, he would have realised that incriminating documents get you nowhere and lead only to interminably dull sub-plots. However, in whatever the opposite of a coup de thèatre is, this master forger had made a rare oversight, and his pocket was revealed to contain an incriminating train ticket that confirmed only what we have known since the end of last series and threw no more or less suspicion on him than was where there already.

Should Mrs Hughes really want to prove her worth as an amateur detective, she’d be better off investigating whatever it is that Thomas has over Baxter – another storyline that has spent an age getting precisely nowhere. But then, this is Downton for you – we’ve known turkeys that have been less overheated.

By the end of the episode, two moments of charm had gone some way to elevating the drama – the first when Uncle Harold gallantly excused Madeline from her father’s pimping games, and the second when Carson and Mrs Hughes finally gave in to so much repressed passion and dared to walk along the sand hand in hand. But truthfully, neither of these were enough to redeem an episode that may well pull in the viewers but is unlikely to deliver the festive feeling of a good tale, well told.

Aired at 8.30pm on Wednesday 25 December 2013 on ITV.

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