After seeing Olive Hawthorne protest the opening of the Devil's Hump on television, Girton claimed "she should been put away years ago." After the Third Doctor and Jo Grant arrived at the Cloven Hoof, he went of the church to inform the Master.
When Bert informed the Master that the Doctor was going to the heat barrier to see Brigadier Lethbridge-Stewart, the Master told Girton to steal the UNIT helicopter and try to kill the Doctor by forcing him into the heat barrier.
Mike Yates saw him getting into the helicopter and tired to stop Girton, but managed to knock Yates out long enough to take off in the helicopter.
Behind the scenes
Girton is renamed Tom Wilkins in the novelisation.