George Thornhill initially planned to develop his Islington estate in 1808, but after a false start he appointed Joseph Kay as surveyor in 1813. When George died in 1827, his son inherited his father’s bequest for improving land in Islington. Street names in the estate recall family connections.
Thornhill Square was begun in about 1847; the railings of its central gardens date from about 1852. Thornhill Crescent was begun in about 1849. St Andrew’s Church, in the central gardens of Thornhill Crescent, was built between 1852 and 1854.
Early residents were well-to-do professionals. As time progressed, the area became run down like much of Islington, and in 1955 the family interest died out with the death of Captain Noel Thornhill.
Thornhill Square and Thornhill Crescent form a large ovoid ellipse, which is a great curiosity in plan. They are largely intact. However, in 1906 two of the houses in the north-west of Thornhill Square were demolished for the new Islington West Library, designed in Art and Craft style by E Beresford Pite.
The central gardens of Thornhill Square were open only to key holders until 1946, when Captain Noel Thornhill donated them to the public; they were opened by the Mayor of Islington in 1947. They were newly laid out in 1953 under the Council’s Open Spaces Scheme as part of the Coronation Year improvements.
This information comes from Mary Cosh, An historical walk through Barnsbury, Islington Archaeology and History Society, 1981.