Mark plays Thomas Brown, the local postman, in the long-running BBC One Sunday night costume drama based on Flora Thompson's series of three semi-autobiographical novels about English country life at the end of the 19th Century.

This world is seen through the eyes of a teenage girl, Laura Timmins (Olivia Hallinan), as she leaves Lark Rise to start a new life under the wing of her cousin, the independent and effervescent Dorcas Lane (Julia Sawalha), who is Post Mistress at the local Post Office in Candleford.

Thomas Brown is the Oxfordshire town's pious postman. Quick to judge others, and keen to correct any sin he sees, Thomas finds it difficult to accept that others don't see the world the same way.