After that frightful pre-wedding squabbling, there was good news straight away this week. The happy couple arrived back from France, which meant Matthew had survived consummating the marriage with Mary. Unaware of the risk he'd taken, he splashed out on a nice new sports car and even, on their first night back, had a go in the Downton death bed itself.

Waking up next to Mary with the carefree cocksuredness of someone who doesn't know they're lucky to be alive, Matthew apologised to Anna for being "en deshabille". Anna stayed sunny and unruffled, partly because discretion is essential for the professional housemaid, but mainly because she was relieved not to have to haul this one out by the ankles and stuff him in a cupboard.

This was a proper, old-school Downton Abbey episode, with the classic themes: sex, love, money, rivalry, and a thing only two people know about, but then they each tell someone and those people also tell someone and then people they've told tell each other that they know, and then everyone realises everyone else knows, and then Lord Grantham finds out.

Welcoming back his new son-in-law, Lord Grantham had pushed the boat out by decanting some of his best wine, presumably the 19th-century stuff. Matthew made himself comfy, knocking back the vino and calling Lord Grantham "Robert". He matter-of-factly told Robbo that yes, he was about to inherit enough money to get the Robster out of the hole he fell in when he invested everything in Titanic Cruises – sorry, I mean the Canadian railroad – but no, he was going to give it all away instead.

Bobby G was finally in the loop and took it manfully, perhaps sensing that this issue would soon rear up and ensure Matthew and Mary had the shortest honeymoon/newlywed phase since Henry VIII and Anne of Cleves. Sure enough, in virtually the next scene Mary was on at Matthew about the inheritance and he was reduced to a quiveringly ineffectual "I do love you so terribly much". Her reaction hinted that the "en deshabille" days are over, sunshine.

Downstairs, new boy Alfred was on the end of one of Thomas's unbelievably unsubtle schemes. The Downton store room evidently keeps the soda crystals next to the dark, coat-incinerating acid: Thomas showed Alfred the wrong bottle and Matthew ended up with a hole in his tails, forcing him to attend dinner in crass attire. Matthew sent his singed coat by train to a London tailor, presumably first class – one's tails can't be squashed against the lower classes. That simply wouldn't do. Then they'd need pressing as well as mending.

Thomas's sabotage came back to bite him when his new enemy, O'Brien, took revenge on Alfred's behalf, leaving Lord G forced to don a dress shirt for Downton's next big nosh-up, when an evening shirt was correct. He might as well have flumped downstairs in beach shorts, a Global Hypercolor T-shirt and a baseball cap with comedy "clapping" hands on the top. With Matthew's tails having missed their return train – they're essential for a white-tie event, but they can't read timetables - the new father- and son-in-law were, in the words of Cora's mother Martha, "dressed for a barbecue".

The gathering, in honour of some extras from the village, was thrown by Mary and the Dowager Countess to pressure Martha into baling Downton out. Mary and Grandmama's plan was already at risk from the DC's pathological addiction to one-liners: those Wildean remarks that, when you think about them, are actually just basic "your mum" insults. Martha's brother didn't like to leave the States, she said. The Dowager: "He hates to leave America. I should hate to go there!" Come on, love, that one needs work.

Now the scheme was threatened by Daisy's blocked oven. Daisy had been suffering from a lack of heat on her stove all episode, literally and metaphorically: as well as moaning about her malfunctioning cooker, somehow she managed to disapprovingly witness almost the entirety of Alfred's fast-developing romance with Martha's thrillingly liberal maid, Miss Reed. They shared a moment in the kitchen - Daisy was in the background, jealously mincing mutton or scraping soot off a horsebrass or something. Later on, Alfred and the wanton Yank kissed outside the meat larder - there was Daisy again, hoiking a wicker basket of venison giblets back to Mrs Patmore. If Alfred and Miss Reed go for the full dessert course and cigar, as looks likely, they need to lock their door.

Back to the oven, and hot dinner was off for the Crawleys and their 20 guests – a drama so great it got the before-the-ad-break treatment, which meant it ranked alongside or even above Mrs Hughes possibly having cancer. No firm diagnosis on that for a while, as the reassuringly Scottish doctor had to send her fluids away for tests. Which train they'd be on wasn't clear.

Martha saved the inaugural Downton Towers Gourmet Night by converting it into a freeform singalong buffet, but then revealed that her assets were tied, leaving the Abbey on the financial edge again.

Two more hot couples had time to emerge. Edith insisted on marrying soppy codger Anthony Strallen: her dad's attempt to split them up by, er, telling Strallen to split up with her failed when she asked his Lordship not to do that and he said, oh all right. Meanwhile in prison, Bates seemed strangely uninterested in Anna's plan to track down and interrogate everyone his evil, dead ex-wife had ever known. Has he become a hardened lag? As he slammed his cellmate up against the wall for threatening him with a razor blade, I thought I saw a glint in his eye.

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