Playing it by the Book...

MARK GATISS TELLS LYNN RUSK WHY HIS NEW DETECTIVE DRAMA IS A 'LOVE LETTER' TO BOOKSHOPS AND MURDER MYSTERIES

- 

"I'm very aware that every detective needs 'a thing'. Sherlock Holmes is the paradigm, and Agatha Christie explicitly draws lines from him to create Poirot," he explains.

"I thought, what if Book was an amateur detective bookseller - and basically, his shop is like an analogue computer."

The set design was also inspired by Sherlock's flat on Baker Street.

"The bookshop is a triumph. It is so cosy. It's a mess - but a mess that you want to spend time in," says Mark. "I wanted to present the bookshop as a kind of oasis for 'othered' people. Jack’s out of prison, doesn’t know why he’s there, but is sort of adopted."

Polly, 59, who plays the scheming but loveable Lady Featherington in Bridgerton, was struck by Trottie’s warmth and positivity as she doesn’t often play those parts.

"She is such a good egg without being sickly sweet. She’s her own person," says the Lancashire-born actress, who has also starred in TV shows including Rome and Line of Duty, along with movies such as Emma and Restoration.