Duggan

Duggan was a detective hired to investigate a plot to steal the Mona Lisa from the Louvre in Paris in 1979. Before this, he had dealt mainly in divorces. He dealt violently with opposition and unfamiliar situations, mainly by hitting people and breaking things, much to the disapproval of the Fourth Doctor. He encountered the Doctor and Romana II while he was watching Countess Scarlioni in the Louvre. He became embroiled in Count Carlos Scarlioni's plot to steal the Mona Lisa, travel back in time and wipe out history. He travelled in the TARDIS with Romana and the Doctor back four hundred million years, where he punched Scaroth unconscious, stopping him before he altered history, the Doctor noting that Duggan had just thrown the most important punch in history which would have allowed Scaroth to prevent life from evolving on Earth. Duggan later bought a postcard of the Mona Lisa from a gift shop at the Eiffel Tower as a memento of the most unusual case he had ever worked on. (TV: City of Death)

He later encountered the Seventh Doctor and Ace in London in 1992, but naturally did not recognise the Time Lord due to him having regenerated. (PROSE: Untitled)