In the funeral scene, Daisy is wearing a skirt that shows the less faded bottom of having been made with a long hem that has since been "let down". This economical step is exactly how the maid's dresses would have been made, to get the most wear out of the fabric, and is even mentioned in "Mrs Beeton's Book of Household Management."
The deadly 1918-1919 Spanish Flu is a misnomer. It did not begin in Spain. Although there are allegations that it made the jump to humans in places as diverse as Austria and China, the first bona fide, verifiable outbreak occurred in Kansas. Because of Wartime censorship, it was not publicized because it primarily affected the military base in Fort Riley, Kansas. The soldiers from Kansas carried it to Europe where British, French, and German troops were infected. It was not reported in those countries either because of Wartime censorship. It was only after it spread to neutral Spain, that other news sources picked it up. As this constituted the first reporting of the pandemic, it became known as the Spanish Flu in the eyes of the public. Initially it was thought to have killed between 20 and 40 million people worldwide, recent research has taken into account Third World and more accurate demographic sources and raised the possible death toll to 50 to 100 million. After mutating several times during a little over a year, by early 1919 the greatest modern pandemic until Covid-19 had mutated again into a much less virulent strain of influenza.
When inspecting the gramophone, Violet quips "You should stand well clear when you light the blue touch paper." "Light the blue touch paper and stand well back" was originally used as instruction for British fireworks and became a way of suggesting someone had done something dangerous or foolhardy and needed to beware of the consequences.
Carson refers to Mary during her childhood as "a guinea a minute," a British colloquialism for a "barrel of laughs," or "a hoot."
Sybil uses the phrase, "Uncle Tom Cobley and all," a British way of saying et al., often to express exasperation at the large number of people in a list. The phrase comes from a Devon folk song "Widecombe Fair". Its chorus ends with a long list of people: "Bill Brewer, Jan Stewer, Peter Gurney, Peter Davy, Dan'l Whiddon, Harry Hawke, Old Uncle Tom Cobley and all."