Tom Cullen is set to join Downton Abbey as a new love interest for one of the main characters.

TVLine reports that the Welsh actor will play a new love interest for Lady Mary (Michelle Dockery), following her husband Matthew's (Dan Stevens) death in a car accident during last year's Christmas special of the period drama.

Cullen will play Lord Gillingham, an old friend of the Crawley family.

The 27 year-old actor shot to fame after his lead role in Weekend (2011), directed by Andrew Haigh. Cullen has also been awarded praise for his roles in Charlie Brooker's Black Mirror and in the miniseries World Without End.