Linen was a fabric stronger and more absorbent than cotton.
During his escapades as Time's Champion, the Seventh Doctor wore a cream linen suit, on the lapel of which he wore Cameca's brooch. (PROSE: White Darkness)
The Twelfth Doctor wore a frock coat of ebony black linen during his last adventures; (TV: World Enough and Time|The Doctor Falls) up to his death. (TV: Twice Upon A Time) His successor, the Thirteenth Doctor, wore it up to when she switched it for a periwinkle trenchcoat as part of her new outfit. (TV: The Woman Who Fell to Earth)