An ambulance man was a member of the staff at Wenley Hospital.
He took a Silurian virus infected Major Baker in his ambulance to the hospital. He was later infected by the virus himself and was taken to the sickbay at the Wenley Moor nuclear research facility. The Third Doctor had Liz Shaw take a blood sample from him, which helped him find a cure to the virus. He was later given the cure, which saved his life. (TV: Doctor Who and the Silurians)
Behind the scenes
Dave Carter, who played the ambulance man, also played the Old Silurian in the same serial. Carter was not credited for this role. (DWM 222)