Smith changed form to match the dominant species of the planet, leaving behind still-mobile and at least partially sentient Husks.
With Light temporarily dormant, he adopted the form of a Victorian gentleman, living in the mansion called Gabriel Chase in Perivale, which had a cellar in which Light's ship resided. By 1883, Smith was the owner of Gabriel Chase, and with Mrs Pritchard and his "ward" Gwendoline, servant Nimrod and houseguest/prisoner Redvers Fenn-Cooper (whom he trained as an assassin), presided over a distorted version of a well-to-do 19th century household.
Smith planned to take over the British Empire by having Fenn-Copper murder Queen Victoria, using an invitation to meet her that he had somehow obtained. The plan was thwarted when Redvers decided to take Control instead. After Control reverted Smith to his former un-evolved state as a form of punishment, he left Earth with the others in Light's ship. (TV: Ghost Light)