Character: Theo Howard
Actor: David Tennant
Episode: A Lesson In Murder

A close friend of the Beales, he comes to help Florence Beale in the aftermath of David's death. Dedicated to the ideals of pacifism, he is enough of a realist to understand that he is capable of killing given the right motivation and he seeks to channel that into military service. By fighting he hopes to do his bit to preserve the freedom of choice for others and to ensure that the ideals of pacifism survive the war.