The glass drawing room at Northumberland House won its fame on account of Adam lining the room with mirror and painted glass, which was further ornamented with gilt metalwork. The drawings show the walls being red and dotted to represent porphyry, while the pilasters, dado and frieze were also in light green. The room was completed in 1775, albeit with minor alterations to Adam’s drawings, including variations to the door frames, overdoors and the ornament to the pilasters.

The interior decoration was altered in 1820 when the south front of the house was found to be structurally unsound and rebuilt by Thomas Cundy (1765-1825), necessitating the widening of the room. The glass decoration to the walls was dismantled and removed prior to demolition in 1874 (see scheme notes).

With the exception of the glass pilasters at David Garrick’s Drury Lane Theatre, Adam did not repeat this heavy use of glass for another interior, perhaps because the room was not used as much as anticipated on account of the Duchess of Northumberland’s long illness and death in 1776.