He was Chairman of the Trustees of the National Gallery from 1933 - 1935, and as Minister for Works in the 1930s he was responsible for embellishing many of London's monuments and parks. As Commissioner of Works, Sassoon was responsible in 1937 for the erection of a statue of Haig in Whitehall, close to the Cenotaph.
He had a reputation for being one of the greatest hosts in Britain. He entertained members of the Royal Family, including the future Edward VIII, and celebrities such as George Bernard Shaw, TE Lawrence and Winston Churchill at his lavishly decorated properties, Trent Park in Enfield, north of London, and Port Lympne in Kent. He presented Churchill with the first black swans for Chartwell in 1920s.