Debbie was the best friend of Susan Foreman at Coal Hill School in 1963. She was born on 23 November 1948 and celebrated her 15th birthday on the day after Susan, their science teacher Mr Chesterton and their history teacher Miss Wright disappeared. She met the First Doctor on at least one occasion, but the Fourth Doctor did not recall ever seeing her before. He also did not remember Susan ever mentioning Debbie but admits that he was not always the best listener. (PROSE: Those Left Behind)