Ray (Delta and the Bannermen)

Rachel Defwydd also known as Ray was a female mechanic and motorcycle enthusiast who came from the 1950's. She was in love with Billy, a professional mechanic and part-time singer at a Welsh holiday camp in Shangri-La. However, her love for him turned out to be unrequited, as he fell in love with the Chimeron Queen, Delta. Despite this she provided valuable assistance for the Seventh Doctor during his confrontation with the evil Gavrok, leader of the ruthless Bannermen. (DW: Delta and the Bannermen)

Behind the Scenes
Ray was originally created with the intention that she would replace Mel as a companion due to rumours that Bonnie Langford was leaving the show, but filming and airing schedules meant that Mel actually departed in Dragonfire and was replaced by Ace. This was confirmed in the Survival DVD Commentary.