Cressida Bonas is to appear alongside Tom Hollander and Ian McShane in 'Doctor Thorne'.

Cressida Bonas

Cressida Bonas

The 26-year-old actress - who previously dated Prince Harry - has been cast in the upcoming drama adapted for ITV by 'Downton Abbey' creator Julian Fellowes from one of his favourite novels by Anthony Trollope.

Fellowes 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."

'Rev' actor Hollander will star as Dr. Thomas Thorne, who lives in the village of Greshamsbury in Barsetshire with his penniless young niece Mary Thorne (Stefanie Martini).

Mary has grown up alongside the Gresham family, whose Greshamsbury Park house dominates the county.

However, Francis Gresham Senior (Richard McCabe) has frittered away the family fortune and now his wife Lady Arabella Gresham (Rebecca Front), their daughters Augusta (Gwyneth Keyworth) and Beatrice (Nell Barlow), and their handsome brother Frank (Harry Richardson) face losing their home.

And when the terrifying Lady Arabella Gresham discovers that her darling son Frank has fallen in love with Dr. Thorne's niece she is horrified.

Her husband Gresham is only being kept afloat by very favourable loans that Dr. Thorne has secured from railway millionaire Sir Roger Scatcherd (Ian McShane).

Cressida - who previously appeared alongside Cara Delevingne in 'Tulip Fever' - has been cast as Mary's friend and confidante Patience Oriel.

The cast also includes Alison Brie, who played Trudy Campbell in 'Mad Men', 'Fortitude's Phoebe Nicholls and 'Ordinary Lies' actress Kate O'Flynn.

Niall McCormick is to direct the drama with Helen Gregory on board as producer.