I missed the first time in the Season 3 Christmas special but it had to do with a nursery game in which the children all had marine names. I forget the other two. Whale and herring, perhaps? Anyhow Rose's father was Shrimp.

True. And to follow the brilliant scheme arranged to bring Marigold to Downton: return her to the Drewe family again until Edith and Cora prepare the Big Lie and then yank her back out. Selfish to the core.

Also Granny has a past, Isobel Crawley finds love again, Tom boots his girlfriend to the curb and the Crawleys spruce up the village. It all wraps up nicely in the last episode and the Christmas finale.