Painter and designer, born in Ware, Hertfordshire. He studied at Bolt Court School of Art and St Martin’s School of Art. Between 1929–39 Horsnell was a graphic artist for various London art studios, then was art designer for motion picture presentation, 1936–9. Was in photographic reconnaissance in Royal Air Force, 1941, then was an official technical illustrator with Ministry of Aircraft Production, 1942–7. Horsnell was noted for his landscapes and townscapes in Britain and abroad. Showed in RA, RBA and elsewhere, solo exhibitions including Harrogate Festival, 1970. Grundy Art Gallery in Blackpool and Lambeth Palace hold examples. Lived in Harrogate, Yorkshire.