Ben Hull portrayed Derwood Thompson on Holby City. He appeared in one non-canon episode of Casualty, "The Road Not Taken", in March 2015. As the events were non-canon, he has never actually visited the ED in the show's timeline.
The events of the episode saw him come into the ED in 2015, when he was called down by the ED staff when Zoe was operating on a patient who was pregnant. She had to get the baby out for the mother to stand a chance. Derwood came down to assist then took the baby up to the maternity unit.