Horace Bernard Milling (1898–1953) was the founder of the Squire Gallery, Baker Street, London, which was the source over several decades of a substantial group of Girtin’s more modest watercolours and drawings. He ran the gallery with Mercie Winifred Milling, née Sanderson (1902–90), who later married the collector and benefactor of the Courtauld Institute Gallery, London, William Wycliffe Spooner (1882–1967).