The actor, who plays the patriarchal Uncle Matthew in the adaption of the 1945 novel by Nancy Mitford, said she had “very sternly” told him how much she loved the source material.
Set in Europe between the First and Second World Wars, the story follows the romantic adventures of Linda Radlett, played by Lily James, the second-oldest daughter of an upper-class family.
West, who is married to landscape designer Catherine FitzGerald, plays Radlett’s father. West and FitzGerald recently released a handwritten note insisting that their marriage “is strong”, after intimate photos of West and his new co-star James were published in the press.
West described his character in The Pursuit of Love as “so outrageous and so politically incorrect”.
He added: “His attitude to life is so not what most people think today in regards to political opinions; how to raise children, the role of women in society they are all so backwards.
“I couldn’t really resist him as he’s so fun to play. Even in the 1930s he had unconventional views but he’s a softie behind it all. My mother in law very sternly told me how much she loved the books and told me not to mess it up.”
West, best known for roles in Les Miserables and The Wire, described Uncle Matthew as “this legendary figure” based on Mitford’s own father.
“He was an old school countryman,” he said.
“Uncle Matthew hunts his children and is quite a frightening patriarchal figure. Pretty much every scene I’m in I’m shouting at someone but because he fought in the First World War he particularly hates the Germans.
“There’s an entrenching tool hung on the wall which reminds him of how he killed 10 Germans in a row.
“He regards everything foreign as unspeakable and cannot imagine why anyone would want to travel or leave England. He would not fare well in a world of gender equality and regards everyone with contempt. But there is a warm heart to him which is why he’s interesting.”
Emily Mortimer has written and directed the three-part series, which also stars Emily Beecham as Radlett’s best friend and cousin Fanny Logan.
West and Dolly Wells feature as Linda’s parents, while Fleabag star Andrew Scott appears as Lord Merlin, the Radlett’s wealthy and eccentric neighbour.
The Pursuit of Love starts on BBC One on 9 May.
Additional reporting by PA