For over two centuries, Number 10 Downing Street has been the traditional residence of the British prime ministers. However, there were exceptional cases to the rule. William Ewart Gladstone, a four-time prime minister, lived in 11 Carlton House Terrace during his first tenure in charge of the country from 1856 to 1875.

Gladstone was a fan of sitting in his study, listening to his daughter Mary play piano, while he enjoyed the view. He was also known to have a case of "keeping up with the Joneses"; he spotted the conservatory on the adjacent balcony of Number 10 and decided to replicate it with even more glass.

Unfortunately, when a bomb hit Carlton House Terrace in 1940, Gladstone's conservatory was destroyed and was never rebuilt. On the other hand, Number 10's conservatory still stands to this day.