Freda Gore
From Tardis Wiki, the free Doctor Who reference
Freda Gore was the wife of James Gore, the mother of Mary Gore and Isobel Gore, and grandmother of Gordon, James and Alistair Gordon Lethbridge-Stewart, and Lizzie Davies. (PROSE: The Forgotten Son)
The Brigadier told the Fifth Doctor that his grandmother died in 1955. (PROSE: The King of Terror)