Clark was a maintenance workman, who, along with Hickman, was in the middle of converting an abandoned sea-fort in the English Channel into a sonar testing station. They were attacked by Sea Devils, who killed Hickman, and when the Third Doctor and Jo Grant arrived, he was frightened nearly to insanity. He dubbed the reptiles "Sea Devils".
Behind the scenes Edit
In the novelisation, he is given the first name of Alan.