Ace is a 16-year-old who first appears in the 1987 serial Dragonfire, where she is working as a waitress in the frozen food retail complex of Iceworld on the planet Svartos. She had been a troubled teen on Earth, having been expelled from school for blowing up the art room as a “creative statement”. Gifted in chemistry (despite failing it for her A-levels), she was in her room experimenting with the extraction of nitroglycerin from gelignite when a time storm swept her up and transported her to Iceworld, and far in her future. There, she meets the Doctor and his companion Mel. When Mel leaves the Doctor at the conclusion of the serial, he offers to take Ace with him in the TARDIS, and she happily accepts
Back in the 1990s Harlequin Miniatures produced a licensed range of 28mm metal miniatures (these are now available from Black Tree Designs) and I bought some blisters. One of these was Ace.