Tom Hollander is to swap his vicar’s dog collar for a stethoscope in Doctor Thorne, the new period drama from Downton Abbey creator Julian Fellowes.

The 48-year-old actor, best known for playing inner city clergyman Reverend Adam Smallbone in the BBC sitcom Rev, will portray Dr Thomas Thorne ITV’s new show, which has been adapted from Anthony Trollope’s novel of the same name.

Doctor Thorne lives in the village of Greshamsbury in Barsetshire, with his penniless niece Mary (Stefanie Martini), and problems arise when she falls in love with Frank Gresham (Harry Richardson), the only son of the local squire.

Prince Harry’s ex-girlfriend Cressida Bonas also has a role in the drama.

Cressida Bonas
Cressida Bonas (Chris Pizzello/Invision)

The 26-year-old, who was Harry’s last serious relationship until they split in April 2014, made her screen debut in 2009 with a small role in the TV series Trinity, where she played a cheerleader.

She will play Mary’s friend and confidante.

Cressida, who has appeared on stage and will star in Justin Chadwick’s drama Tulip Fever alongside Dane DeHaan, Christoph Waltz and Dame Judi Dench, joins the star-studded cast, which also includes Ian McShane.

Rebecca Front
Rebecca Front (Daniel Leal-Olivas/PA)

The Thick Of It’s Rebecca Front, Scottish actor Richard McCabe and Phoebe Nicholls have also signed on for roles in Doctor Thorne, alongside American actress Alison Brie, who starred in Mad Men and Community.

Julian Fellowes
Julian Fellowes (Ian West/PA)

Julian said: “Doctor Thorne is a wonderful example of Trollope’s gift for understanding the tangles we humans get into.

“He is sharply observant, critical and merciful in equal measure and, above all, highly entertaining. With the cast we have assembled, I am confident we can bring all of these qualities to the screen.”

Filming on the three-part drama, directed by Niall McCormick, begins later this month.