What happens in the library, stays in the library.
They slowly began to put their clothes back on. They certainly knew it was risky. No one who's thinking clearly would decide to have sex anywhere outside their bedroom. But when the two of them were together, Cora and Robert weren't thinking clearly. Couldn't make sensible decisions. They could only think about each other, about their wonderful marriage. Surely, they knew it wasn't "the proper way" as Mama always put it; they knew, it was not what one expected from the Earl and Countess of Grantham. People in their position should keep that part of their marriage in their marital bed. But why waste a perfectly lovely afternoon when no one was home? Mary, Tom and Edith had gone out with the children, they had given the staff the afternoon off (and the only ones present in the house were Mrs. Patmore and Daisy- and what were the odds of them coming into the library?), so they had decided to have some "terrific fun" on their preferred settee in the library.
"You know, I really am embracing the new fashion." said Cora, as Robert helped her put her corset back on. "Mmm…" was Robert's response. Cora rolled her eyes. "It's only to your advantage, Robert, it took you years and years until you were able to do and undo the laces of my corset… but now it's just so… easy. And fast." Cora had now started to put on her dress, while Robert put on his trousers. "Well I suppose you're right, darling. I may not like to admit it, but not all change is bad. Some of it is actually very… helpful in certain situations." Cora giggled. "Don't let Mama hear you say such things."
"Well, my dear, it can't be worse to hear such things than to see them with my own two eyes!", Violets' voice called from the door. Robert and Cora – him with his pants on, but shirt unbuttoned; her almost in her dress, but still rather exposed – froze. "Now", Violet continued "would you be so kind as to make yourselves presentable again, so that Isobel and I can come in and have some tea?" It was just in that moment that Cora and Robert realised Violet wasn't alone. Given Isobel's expression, she seemed to be very amused, but tried to hide it by pretending to be shocked. Cora, who finally managed to put on her dress, walked towards Isobel. "I am so sorry Isobel, we thought we'd use the time to our advantage… you know – having the house to ourselves. We certainly weren't… expecting visitors this afternoon." "Yes, we can see that", Violet said. Isobel looked from Violet to Cora and responded: "Oh please don't be sorry. We shouldn't have come without calling." "Yes, I agree", Violet stated "we were obviously interrupting something..."
"Mama!", Robert shouted, more embarrassed than infuriated. "Oh please, Robert, don't let's pretend that this is the first time I have interrupted your… marital activities." With every word Violet said, Cora's face turned a darker shade of pink. Isobel was surprised: "This a regular occurrence?", then she turned to Violet, "Why have you never said anything?"
"You see, my dear, many years ago we concluded that what happens in the library, stays in the library."