The Grand Auctioneer was the owner of the Lifemarket on Bryce's Asteroid.
As a young man, he majored in genetics and horticulture on the planet Bryce. One day, he learned how to reanimate dead cells. He was exiled from Bryce and opened the Lifemarket on Bryce's Asteroid.
When the Sixth Doctor and Peri visited Bryce's Asteroid, he took a liking to Peri. He thought the Doctor was a reanimated, but malfunctioning, dead body and had him sent to the workshop to be fixed.
When the Doctor ruined his business, Peri suggested he go back to topiary, as he was very good at it. (PROSE: A Star is Reborn)