The Ballroom Vestibule as one enters from the south portico and approaches the State Ballroom. At the centre of this semi-circular room is a fiddleback blackwood table crossbanded with inlaid exotic timbers, with rosewood side chairs at radial points. The patterned mouldings, stencilled fleurs-de-lys and colour scheme anticipate the decorative scheme of the ballroom. Guests at balls and other State receptions enter this room through a porte-cochère (or carriage entrance) on the south side of the house.

Windows facing onto the Fountain Court are visible through the left side door, and a curtained arch leading to the supper room through the right side door. The vestibule is part of a four-tiered structure, like the entrance to an opera house, with its own roof line and double portico. Above the vestibule is the Musicians' Gallery.