MATTHEW CRAWLEY

Well now, this is a shock. Apart from Mary and Edith, they have all been taken by complete surprise, and cousin Robert's reaction is terrifying to witness. He has never seen the Earl so furious, so suffused with anger. Cousin Cora's response is just as frightening – she looks like she might shatter into thousands of tiny pieces.

He would not want to be in Branson's shoes for anything. But he has to hand it to the man – he has courage, fronting up to Robert like this. Matthew doesn't know if he'd have the backbone to stand in front of a room of people, including the formidable Dowager Countess, and drop such a bombshell.

Who'd have thought it, a grand passion between cousin Sybil and the chauffeur? How do a lady and a servant even get well enough acquainted to have conversations, let alone fall in love? Especially at a place like Downton. The distance between classes in this household is astonishing, and there are times when he thinks the staircase down to the lower floor should be a mile long, such is the gap between those who live upstairs and those who work downstairs.

So the fact that an Irish chauffeur has managed to woo the daughter of an earl is really quite remarkable.

He knows Sybil does not see the division between the classes the way most young ladies of her standing would but to go from being sympathetic towards the working class to marrying a member of it – well, that's an enormous leap. She must be very certain in her feelings for Branson to take such a drastic step.

He must admit, there have been times when he has wondered why a girl as attractive and sweet as Sybil has not had a beau. He knows the fact that none of the Crawley girls are yet married has had tongues wagging in society. Mary might be engaged to Sir Richard but she seems in no hurry to make their union official. Edith's name has never been been seriously linked with any man other than Sir Anthony Strallan and that came to nothing. And Sybil has just seemed too wrapped up in her nursing career to be interested in settling down.

Of the three sisters, he could quite easily believe it was possible for Sybil to marry first, despite the fact she's the youngest by some years. Looking at the situation in a detached way – something his training as a lawyer has taught him to do – he can see that many would-be suitors might be put off by Mary's apparent glacial demeanour and Edith's air of resigned bitterness.

But Sybil is pretty and lively and appealing and while there may be a wilful streak, some men would see that as a challenge. So an announcement that she would be the first of the sisters to be married would not have come as a surprise. But the intended groom most definitely has.

How long has this liaison with Branson been going on? Could it possibly date back to the night of the count in Ripon all those years ago when Branson had scooped her up in his arms after she was injured in the skirmish? That evening had been a memorable one for him as it was the night he proposed to Mary, and he recalls her telling him over sandwiches in the dining room how Sybil had stood up for Branson to her father and threatened to run away. Had she been in love with him way back then?

And if he remembers rightly, there had been something not quite right about Branson's concerns for his young mistress. He recalls now how desperately worried the man was, how terrified he looked when she lay bleeding on the ground. He had thought it was because Branson feared losing his job but maybe there was more to it. Maybe that was the start of it all.

If only he'd known about the relationship building between them. Perhaps he could have done something about it. Matthew has always been so fond of Sybil – he has thought of her as a little sister over the years and has tried to look out for her welfare when necessary. If only Mary had confided in him about Branson's pursuit of Sybil, he could have stepped in and saved the day, prevented it coming to this. He could have taken Branson aside, had a man-to-man talk with him, pointed out how inappropriate the whole situation was. But he had not been given the chance. Mary tells him nothing of consequence these days.

And why should she? She has Sir Richard now, like he has Lavinia.

He looks down at Lavinia now. Lovely Lavinia. She's so sweet, so trusting. She is everything Mary is not, and that is the problem. He loves Lavinia but he longs for Mary. Even now, as much as he's fighting it, every cell in his body is drawn to Mary as she sits on the sofa a few feet away. In just a few short days he's expected to formally hand his heart to Lavinia but in fact it was snatched away a long time ago by Mary.

He shakes his head as he realises he envies Sybil and Branson. Their love is so very complicated and they face a very difficult road ahead. Yet they are pushing aside all the details to acknowledge the simple truth that they want to be together. They know what they want and they have the courage to go out and get it.

He glances towards Mary. If only he could be that brave.

Next: Lady Mary

The more she thinks about the ridiculous thing Sybil is doing, the more she seethes with anger that almost rivals that of her father. But there is another emotion too, one that is swirling through her veins along with the fury and the disappointment. It takes her a moment but she eventually realises what it is: jealousy.