Physics teacher (School Reunion)

The usual physics teacher at Deffry Vale High School was said to never have played the lottery when she won; she was given the ticket through the door at midnight. In 2007, the Tenth Doctor replaced her, unlike the other new members of staff, whose predecessors, according to Mr Parsons, had the flu three months earlier. The Doctor simply responded, "The world is very strange." (TV: School Reunion)

Behind the scenes
After her only on-screen mention in School Reunion, other Doctor Who media has given the Deffry Vale High School physics teacher several different names and accounts of her lottery win. According to the Deffry Vale website, her name was Victoria Mehru. The Deffry Vale High School website meanwhile said the science teacher who won the lottery was Ms Mehru, but also said the teacher the Doctor replaced was Ms Barrat. The 2015 book The Time Lord Letters by Justin Richards gives the teacher's name as Miss Morrison. Meanwhile, an in-universe newspaper article in The Secret Lives of Monsters, also written by Richards, names her Lucille Beneluct.