[2][3] The Duke left his wife entirely in charge of the design and building of Marlborough House; she wanted her new home to be "strong, plain and convenient and good".

This led John Vanbrugh to joke that the Duchess had "the direction in chief to herself, with Sir Christopher Wren as her Deputy Surveyor.

Wren had designed and built a gateway arch and screen in the front courtyard with this entrance in mind, which survives as a grotto.

[8] In the 1770s, the 4th Duke of Marlborough hired the architect Sir William Chambers to add a third storey to the house and architectural details like new ceilings and chimneypieces.

[17] From 1861 to 1863, Sir James Pennethorne substantially enlarged the structure by adding a range of rooms on the north side and a deep porch for the Prince and Princess of Wales, later King Edward VII and Queen Alexandra, who made their home the social centre of London.

[18] Their second son, the future King George V, was born at Marlborough House in 1865, and the family lived there until Queen Victoria died in 1901, when Edward acceded to the throne and they moved to nearby Buckingham Palace.

From the 1880s the term ‘Marlborough House Set’ came into usage to denote the Prince of Wales's fast-living social circle, which included gamblers, bankers, and other "raffish" individuals.

[19] After his father moved to Buckingham Palace in 1901, Edward VII's son George, now Prince of Wales, took up residence with his wife Mary and their children.

A late Art Nouveau-Gothic memorial fountain by Alfred Gilbert (1926–32) in the Marlborough Road wall of the house commemorates her.