In 1968, whilst dating George Wilson, Doris Lethbridge-Stewart gave birth to a son named Albert Wilson. However, this son was not Wilson's, but rather Alistair Gordon Lethbridge-Stewart's. George Wilson took the boy on as his own.
Doris wrote a letter to Alistair to tell him he had a son, but she never sent it. (PROSE: The Enfolded Time)
Later, on 1 January 1990, Albert finally made contact with his biological father, not wishing his soon-to-be-born daughter to be without a grandfather. (PROSE: The Enfolded Time) It was through this that Alistair and Doris met again and eventually married. (TV: Battlefield)