In 1875, Mrs. Arabin lived at No. 36, and Lord Sandon, eldest son of Lord Harrowby, at No. 40.
In the 1900s, Howard Vincent was at No. 1, the Duke of Portland at No. 3, Earl Fitzwilliam at No. 4, the Dowager Duchess of Manchester at No. 5, Lord Farquhar at No. 7, Sir Arthur Hayter at No. 9, Col. Ralph Vivian at No. 15, the Italian Embassy at No. 20, Lord Strathcona at No. 28, the Marquis of Bath at No. 29, Lord Calthorpe at No. 38, Lord Durham at No. 39, Sir Charles Tennant, at No. 40, and Sir Ernest Cassell at No. 41.
Of those named, several were at various times elected Trustees for the Square: in 1884 Sir Charles Tennant acted as such; in 1894, Lord Calthorpe; in 1896, the Duke of Portland; in 1900, the Duke of Somerset and Lord Farquhar; in 1902, Lords Durham and Bath; and in 1904, Lord Fitzwilliam, in addition to various other noblemen and gentlemen. In 1907 the garden committee consisted of Sir Howard Vincent, Lord Newlands, and Col. Ralph Vivian.