David Campbell

David Campbell was a freedom fighter fighting on Earth during the Daleks' invasion and occupation of Earth (2157 - 2167). He encountered Susan when she and the Doctor, Ian Chesterton and Barbara Wright landed in London.

With his help they stopped the destruction of London and helped destroy the Daleks. He and Susan quickly fell in love, she stayed with him to help restore the Earth. (DW: The Dalek Invasion of Earth)

David and Susan spend at least 30 years together, however by the time that David is 54, Susan still looked 18. (EDA: Legacy of the Daleks)