As the sun rose on Edith's big day, how excited she was. "Something happening in this house is actually about me!" she beamed. In series two, the Great War magically converted Edith from a bitch to a saint – so some good came of it all – which means we want her to be happy. But, really, she might as well have been cycling gaily on a crumbling cliff edge. Poor Edith.

Before the inevitable wedding fiasco, there was downstairs business to take care of. Thomas launched another of his incredibly unsubtle schemes, putting Molesley up to starting a rumour that O'Brien was about to resign.

There were only three flaws in this brilliant plan. One, moving jobs isn't actually an intrinsically bad thing to be doing. (Spreading it around that O'Brien was putting turmeric in Lady Cora's eyeshadow, or that she had five children born out of wedlock living under her dress - that might have done damage.) Two, as soon as someone asked O'Brien about it, she said it was bunk and the talk stopped. Three, Molesley was always going to grass Thomas up.

O'Brien confronted her former ally and promised revenge – their new Alien v Predator relationship should boil up nicely in the near future, especially since O'Brien's payback is likely to involve broken bones at a minimum.

The other big servant scheme was Carson going Columbo on Mrs Hughes's illness, in a return to the series one glory days of a plotline being set in motion by eaves-dropping. Mrs Hughes and Mrs Patmore were minding their own business, shouting about cancer in the middle of a passageway. Unbeknownst to them, Carson was standing in plain sight fourteen inches away and overheard. He sprang into action.

The wily sleuthing butler first hoodwinked the reassuringly Scottish doctor, then Mrs Patmore, into revealing details using the old pretending-to-know-already trick. "I know all about that thing, y'know," said Carson, eyebrows oscillating. "Oh, you mean Mrs Hughes's cancer?" they replied. I paraphrase, but that was the gist.

The Hughes news brought out Downton's best enduring theme: people expressing how much they love each other when professional or class boundaries say they shouldn't. In a lovely scene between Cora and Mrs Hughes, the lady of the house told her employee that there'd always be a death bed for her at Downton if necessary.

Below stairs, it's been fairly obvious since day one that Carson is gooey for Hughesy, but this was now overt. He fretted over her prognosis as if they'd been married for decades, which they basically have been.

Ahead of the nuptials, the Downtons planned for their imminent homelessness by looking the last resort resolutely in the face. The aristocratic equivalent of scrambling together warm clothing, a sleeping bag and the best cardboard boxes on offer round the back of Asda was Downton Place, a cubby-hole whose poxy 18 bedrooms would only need eight servants to maintain. Lord G and the gang faced the prospect with fortitude. "We still own most of the village," he said, in a valiant effort to find a bright side.

When the clan got back to the Abbey, Mary and Matthew flared up again after a letter arrived from Lavinia Swire's dead dad's people. The crux of it was that Lav had written to him, on her death bed, to say she hadn't minded being second best. In their room at night, Matthew was furious with the new Mrs, er, Crawley for opening his mail.

His surprise that this sort of thing should happen underlined how new their marriage is but, more importantly, the lateness of the hour gave us something we've not seen before: Matthew being angry in a dressing gown. Many actors would struggle here but, having mastered it easily, Dan Stevens went several steps further. He gave us angrily taking off the dressing gown, angry in pyjamas, angry slipper removal, and angry in bed.

A Bafta must follow. Anyway, Matthew's kerrazy suspicion that Mary had forged the letter was dispelled when Mary bravely went downstairs to ask the slaves. Daisy owned up to posting Lavinia's swansong. "She was ever so nice. I still get sad when I think about her," she said, a line slightly undermined by the fact that air makes Daisy sad. But it meant Matthew could save Downton and rescue everyone from that frightful 18-bed semi.

Anna and Mr Bates carried on fighting for his life and freedom. While Anna paid a washer-woman to give her Mrs Bates's last known movements - dull details that must be useful later - Bates was the subject of a prison sting. Someone had hidden something in his bedclothes, but Bates was tipped off by the other man in the prison who looks too sensitive to be there and probably isn't guilty. Just before the screws came to search, Bates found the item – snuff, I think, although it looked like a carpet sample – and secreted it. A handy hole in the wall meant he didn't have to use the standard prison method. Is his luck changing?

Edith's luck was out. At the altar, Anthony Strallen bolted. "Don't stop him doing the only sensible thing he's come up with in months," said the Dowager Countess, tender as ever, and off he staggered. Carson was furious, the staff back at home were bemused by their sudden inheritance of asparagus and lobster, and Edith resigned herself to being a spinster.

As for Mrs Hughes, she left Mrs Patmore outside the doctor's room and got the news herself. A benign growth, she told Mrs Patmore, who relayed this to Carson. He began singing and polishing plates with new brio. Mrs Hughes smiled at this, but a nice bit of acting from Phyllis Logan told us it was a bluff. Rewatch the last half-second of the episode if you missed it.

>> Series three, episode two: Matthew survives, Daisy's oven explodes

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