A design for a 'Royal Gallery' had been made by Soane as early as July 1822. This was to form, in his own words, 'a national monument to be decorated with paintings, bassi-relievi & statues to perpetuate the glorious achievements of British valour by sea & land' (SM 71/2/84). Further designs were then made in December of the same year (SM 71/2/67-70, 85), at which stage the project must have been put on hold because the next designs were not produced until July 1823 (SM 71/2/81). Whereas the earlier designs had been based on a remodelling of the Prince's Chamber, old House of Lords and the Painted Chamber, the new designs were for an entirely new building consisting of an ante room and a three-bay gallery with a cupola, with committee rooms and offices to the east.* An estimate of £21,800 was approved by the Lords. Construction began soon after, on 3 October 1823, and within just four months the Royal Gallery was finished. The committee rooms were completed by the summer of 1824, some £24,527 having been expended. To reward them for the speed and efficiency with which they had worked, Soane treated the workmen to a dinner at the Freemasons' Hall, for which he was duly (and unfairly) reprimanded by Col. Stephenson of the Office of Works, even though Soane had absented himself from the celebrations. (A. T. Bolton, The Portrait of Sir John Soane, 1927, pp. 370-1).

The new buildings attracted criticism from within the House of Commons. Firstly the demolition of the medieval Prince's Chamber and the old House of Lords was condemned as 'almost sacriligeous' (Sir J. Mackintosh), and secondly the new Gallery was attacked as 'strange and anomalous...a thing of such strange and absurd proportions that it was impossible to look at it without a feeling of disgust' (Henry Bankes). The Royal Gallery was further criticised in an anonymous article in Knight's Quarterly Magazine, ('The Sixth or Boetian Order of Architecture', vol. II, London, 1824, pp. 446-63) (q.v. P285).

*Survey drawings of the Prince's Chamber were made by Charles Papendiek in August 1823. Four of these drawings are held by the Westminster City Library and two are in the National Archives, Kew.