Brown
Walnut was a dark shade of brown named after a certain nut.
The Fourth Doctor wore a walnut trenchcoat when going to check Earth on 16087, (TV: The Ark in Space) when he fought Field Major Styre of the Sontaran G3 Military Assessment Survey and tricked his marshal into cancelling an invasion of Earth. (TV: The Sontaran Experiment)
The War Doctor wore a double-breasted trenchcoat of walnut leather with peaked lapels when he, Fey and the Sisterhood of Karn fought Mark VIII Daleks and the Morlontoa of the Seventh Sky on the Dorian Nexus. (COMIC: The Clockwise War)
The Tenth Doctor wore a walnut brown tie with stylised peacock-eye steel blue and brown motif in honeycomb grid when he helps Elton Pope and meets an Abzorbaloff, (TV: Love And Monsters) during the Battle of Canary Wharf involving Mark VII Daleks including the Cult of Skaro versus Cybus Cybermen including Cyber-Leader One and Cyber-Leader Two as well as the fall of Torchwood One including Yvonne Hartman, (TV: Army of Ghosts|Doomsday) when recruiting Martha Jones after the Royal Hope Incident, (TV: Smith and Jones) when he and Martha join forces with William Shakespeare to defeat Carrionites on Southwark during 1599, (TV: The Shakespeare Code) when saying goodbye to the Face of Boe after helping him save New New York from Macra during 5,000,000,053, (TV: Gridlock) when meeting an older Tim Latimer during an Armistice Day, (TV: The Family of Blood) during an encounter with Pyroviles and Pompeii's volcanic end on 79 AD, (TV: The Fires of Pompeii) when he and Donna Noble encounter a Time Beetle from the Trickster's Brigade, (TV: Turn Left) during the Planetary Relocation Incident involving Davros and the New Dalek Empire as well as his siphoned regeneration which spawned the Meta-Crisis Doctor, (TV: The Stolen Earth|Journey’s End), and when he met Christina de Souza and space stingrays. (TV: Planet Of The Dead)
