SM volume 74/46 and SM volume 74/47 focus on decoration for the lantern of the central dome, which was not realised and SM volume 74/43, SM volume 74/44, SM volume 74/45 and the verso of SM volume 74/46 show the structure of the circular roof of the lantern and the supporting piers, as executed. The working drawings, particularly SM volume 74/44, are useful in showing the junction of roof, pin and cornice for the lantern pier. It shows Soane's careful attention to structure and technology.

The drawings employ a combination of elaborate diamond patterns and scrolling foliage, however the decorative scheme of the lantern was simpler. In the executed hall, the pendentives were striated and rosettes decorated the spandrels.