Believing Earth was becoming too polluted and humanity was too corrupt to change, they developed an elaborate plan to restart civilisation. After evacuating London by bringing dinosaurs to modern times with time eddys, they planned to reverse time around the planet to a period before mankind had evolved, then colonise it with a select group of people who believed they were on a spacecraft heading for New Earth.
The plan was exposed and defeated by the Third Doctor, Sarah Jane Smith and UNIT. Sarah exposed the truth about the spaceship to the colonists, horrifying them since the plan would wipe out whole generations of humans and of history, while the Doctor and UNIT identified the people responsible for the project. Grover and Whitaker transported themselves to a time in the past after attempting to activate a time machine that had been reprogrammed by the Doctor. Finch was subjected to a court-martial and Yates was given sick leave and the chance to quietly resign. (TV: Invasion of the Dinosaurs)