As a building with a more than 900-year history, the architecture of Windsor Castle is, naturally, very complex. It can best be understood by consulting Tyack, Bradley and Pevsner, The Buildings of England: Berkshire, pp. 616-95.
George IV inherited Windsor Castle on his father's death in 1820. Several improvements had been made for George III by James Wyatt in 1800-14 but his alterations quickly fell out of fashion. Further repairs were carried out by Robert Smirke until the King deemed that more substantial alterations were necessary. Soane was summoned by Sir Charles Long, George IV's adviser on the arts, to discuss these improvements on 23 November 1823. Soon after the decision was made to hold a competition, for which Long drew up lengthy guidelines on the nature and the character of the work to be undertaken. Soane and Smirke were invited to submit designs, together with John Nash and Jeffry Wyatt. Although several survey drawings were made for Soane between 5 January and 10 February 1824, he does not appear to have submitted any designs - perhaps, as suggested by M. H. Port, he was too preoccupied with the rebuilding of the Royal Entrance to the House of Lords and the ongoing argument over the style of the Westminster Law Courts (King's Works, VI, p. 384). The competition was won by Wyatt (who subsequently became 'Wyattville'). The drawings catalogued here, therefore, provide an important record of the Castle prior to the alterations carried out by George IV.
Drawings - appear to be Office of Works drawings given to Soane for him to make copies. These pre-date James Wyatt's alterations. Drawings  and  are copies of two of these. The rest, also potentially copies, were made in Soane's Office. The Soane Office Day Books record drawings for Windsor Castle being made by David Mocatta and Stephen Burchell. It is unclear why, then, drawings  and  are signed by Charles James Richardson, who did not in fact become a pupil of Soane until February 1824. Similarly the inscription of 'Bank of England' at the bottom of several of the drawings is unexplained.
Literature: M. H. Port, 'Windsor Castle and Lodges', in J. M. Crook and M. H. Port (eds), The History of the King's Works, VI, 1973, pp. 373-84; G. Tyack, S. Bradley and N. Pevsner, The Buildings of England: Berkshire, 2010, pp. 616-75.