Winston Katusi was an elderly Londoner living in the early 21st century. He was a friend of Wilfred Mott, and a member of the Silver Cloak that Wilf sent out seek out the Doctor. Winston, Wilf, and the other Silver Cloak members used a mini-bus to follow the Doctor's movements. They would locate him in the wastelands of London, and Winston joined the other members of the Silver Cloak in posing for a photo with the Doctor. Winston and the other Silver Cloak members dropped Wilf and the Doctor at a coffee shop before driving off.
Later, the Master activated the Immortality Gate to superimpose himself onto the entire human race. Winston managed to telephone Wilf just prior to transforming into a version of the Master. The Master's actions were later undone by Rassilon, and Winston reverted to being human. (DW: The End of Time)