Last night's viewing: Downton Abbey, IVT1 9pm

This means war! The grandes dames of Downton have come out fighting

Shirley MacLaine as Martha Levison and Dame Maggie Smith as Lady Grantham in last night’s Downton (Carnival Film & Television Limited)

But for the Franklin Mint pretensions that surround ITV's flagship costume drama, the third series of Downton Abbey might most appropriately have been trailed as a Vegas boxing bout.

In the red corner, Violet "The Crusher" Crawley, a woman who can sour milk with a social observation. In the blue corner, the challenger, Martha "The Democrat" Levinson, arriving from America to sneer at the hidebound traditions of the aristocracy.

Between them, Maggie Smith and Shirley MacLaine probably don't add up to a single bantamweight, but they're big hitters for all that – and Julian Fellowes knew how to tease us with the prospect of combat between these two grand dames.

"I'm so looking forward to meeting your mother again," Lady Grantham said to Cora, "When I'm with her I'm reminded of the virtues of the English." "But isn't she American?" said Matthew, rather dimly. "Exactly", she said, tartly.

You never start with the main event, of course. We had to wait for those two to clash, but there was plenty on the undercard to keep us going till then – including the occasional prison visit to Bates so that Anna can display her loving pluck, and a scrappy battle between hot-headed Fenian idealism and English class consciousness. Branson the chauffeur and Lady Sybil were back from Ireland for Lady Mary's wedding to Matthew, and the former was in no mood to soft-pedal his politics to ease the awkwardness in the drawing room. Meanwhile, Lord Grantham had been getting bad news about his railway shares; Cora's fortune has all but gone and Downton's future hangs in the balance, only a highly convenient legacy for Matthew offering any prospect of rescue. Unfortunately his conscience won't let him accept it – an ethical nicety that briefly threatened a last-minute cancellation of the wedding. The Earl's hopes for family economy seem a bit forlorn too: "An aristocrat with no servants is as much use as a glass hammer," sniffed the Dowager, when cutbacks were hinted at.

Dinner was a lively affair, stimulated by a bit of skullduggery from an old flame of Sybil's, who'd slipped Branson a Mickey Finn. Disinhibited at the best of times, he started bellowing at the other guests, sending Sybil into paroxysms of misery, before the noble Sir Anthony exposed the plot and provoked Matthew into an implausible gesture of gallantry; having apparently neglected to choose a best man until just days before his wedding he nominated Branson for the post.

In Fellowes' universe the English aristocrat is, at heart, one of nature's noblemen too, and thus implicitly entitled to the advantages he enjoys. As if to underline the fact that it's only the occasional bad apple that gives the breed a bad name, the cad's father barked at his son as well.

As for the big fixture – well, Martha will no doubt hold her own in coming rounds, perhaps even win some – "Now you must tell me all of your wedding plans", she said as she greeted Mary, "and I'll see what I can do to improve them."

But in the first real confrontation with her main opponent, it was the Dowager who landed the hardest punch: "Oh dear, I'm afraid the war has made old women of us both," said Martha after embracing her rival matriarch. "Oh, I wouldn't say that," replied Violet, "but then I always stay out of the sun."

Round one to the home corner, I think, but there are seven more to go before it's over.