Potential to set up stories for future films, such as Branson (Allen Leech) who meets a new love in the form of Lucy (Tuppence Middleton) the maid of Lady Maud Bagshaw (Imelda Staunton) whose father was the Earl's (Hugh Bonneville) great uncle . But she's not really the maid, or companion as she's going to be known as later on, but her daughter. A secret discovered by Isobel (Penelope Wilton). She's the heir to the estate that the family were hoping the Earl would inherit as a male heir and distant cousin. As the Dowager (Maggie Smith) was determined to have it out with her once and for all. Changing her mind when she finds out the truth. Again saying she would've understood as she's not that set in her ways. Edith (Laura Carmichael) pushing for Branson and Lucy to get together just to keep the fortune in the family. Under the guise of wanting something better for Branson.
Mary (Michelle Dockery) worries over whether Downton can sustain itself and comments on finding herself putting out the chairs for the village in the pouring rain. Anna (Joanne Froggatt) tells her to think of the staff and people all over the county who rely on the estate. Also Mary conveying this concern to the Dowager who has her own secret to confide in with Mary. That the doctor hasn't given her much time and Mary will really miss her "granny." The General Strike of 1926 is alluded to only just in passing.
Carson (Jim Carter) is brought out of retirement and can no longer tend to his weeds as Mary wants him at Downton when the Royals arrive. Barrow (Rob Collier-Smith) doesn't want to polish the silver and wants to leave it up to the Royal's own staff/servants. Of course he's perturbed by this and walks out. The Earl won't be firing him as he's amazed by Barrow's sudden discovery of principles. Barrow too finds his own potential love interest in Richard Ellis (Max Brown) the King's valet/dresser and they agree to meet in York for a drink. Barrow gets taken in by someone else at the pub and they end up in a secret location for gay men. Finally there's a raid and he's arrested and ? gets him out of jail by using the Royal status on his calling card.
The staff are in uproar as they won't be able to wait on royalty or prepare food for them. Mrs Patmore (Lesley Nicol) even goes out to buy food when she doesn't need to. With the pompousness of the Royal staff party and specifically the attitude of the Back Stairs butler Mr Wilson (David Haig) and the French chef, Courbet (Philippe Spall) the Downtown staff stage a mutiny. Deciding to have the royal staff taken away by the pretext of being needed in London and locking up Wilson in his room. With Anna giving the Courbet a sleeping draft, double does. Moseley (Kevin Doyle) is particularly thrilled as he gets to wait on Royalty and puts his foot in it by impertinently replying to Queen Mary. Shocks all around then. As Cora (Elizabeth McGovern) has to apologize on his behalf.
A sub-plot with the Irish situation is added for extra interest for Branson to get involved with. As he's approached by a suspicious man, he thinks is spying on him, regarding his feelings towards the Irish and the royals. But Branson's been subdued by the Crawley family in his feelings. He gets to catch said bloke at the parade as he tries to assassinate the King. Mary had to get in on the act too of course. Later the ball the King reveals he knows exactly who Branson is and what he did.
The opening follows the letter informing of the arrival of the Royals arrival at Downton from a train, to the mail van, a postman on a motorbike, until it's safely delivered to the Castle. Until the familiar bells of the house ring out to the servants. So you know you're in familiar territory. You'd think the staff's actions would've got a sterner reprimand for their actions, however it's just casually laughed off except for the Earl taking exception at Moseley's actions. A nostalgic reminiscence for fans of the original series.