Who was Britain's oldest Prime Minister and lived in the Seaforth House built for his father? 
Seaforth House: Seaforth House was a mansion in Seaforth, Merseyside England built in 1813 for Sir John Gladstone, father of William Ewart Gladstone who was Prime Minister of the United Kingdom four times. William Ewart Gladstone:  Gladstone was also Britain's oldest Prime Minister; he resigned for the final time when he was 84 years old.
William Ewart Gladstone