Learn all about the new book from Jessica Fellowes in the time it takes you to make a cuppa.

1. Why the Mitford sisters?

The six Mitford sisters encapsulate everything that was extraordinary, exciting, glamorous and political about the period between the wars – long an era of fascination for me. In focusing on a different sister for each book, I can explore the changing landscape between 1920 and 1939.

2. How did you learn about the unsolved crime this book is based on?

My editor, Ed Wood, spotted a news story about it when we were in the early stages of plotting. He sent it over to me and when I discovered that the murdered woman was on her way to visit friends in the same town that the Mitfords’ real-life nanny’s twin lived in, we had to use it!

3. How did you create the series heroine, Louisa Cannon?

I knew that I wanted my heroine to be someone who moved between both upstairs and downstairs, so while the girls are young it makes sense for her to work in the nursery. I have lots of images of the 1920s that I use for ideas, as well as the research that I did for the Downton Abbey books. But ultimately it came down to the fact that I wanted someone I could spend a lot of time with as she will feature in every book of the series – so she is smart, quick and ambitious.

4. Do you have a favourite fact you found out during your research for The Mitford Murders?

Forensic science for crime-solving began in the early 20th century and remained pretty much unchanged until the discovery of DNA. Dr Spilsbury, who did the post-mortem of the murdered woman at the centre of the book, was considered the ‘father of forensic science’ – he identified decaying human remains in a cellar as those of Dr Crippen’s wife.

5. Describe your book in five words.

Vintage, glamour, war, crime, sisterhood.

THE MITFORD MURDERS is out September 12.

JESSICA FELLOWES is the author of the worldwide no.1 bestsellers THE WORLD OF DOWNTON ABBEY and its follow-up, THE CHRONICLES OF DOWNTON ABBEY. Jessica started as a journalist at the Mail on Sunday, going on to be the Deputy Editor of Country Life magazine, before deciding to focus on books.