This model from the MEWS photo archive is a 1:4 scale De Havilland Gipsy aero engine made to the Les Chenery design, pictured here on display at a Harrogate Exhibition. The de Havilland Gipsy is an air-cooled four-cylinder in-line engine designed by Frank Halford in 1927 initially as an upright 5-litre engine, although later versions were designed to run inverted, with increased capacity and power.
The Gipsy was one of the most popular sport aircraft engines of the inter-war years and the engine of choice for various other light aircraft, trainers, liaison aircraft and air taxis. It continued well after the end of  World War II and established the company as an engine as well as aircraft manufacturer.  Gipsy engines are still in service in vintage light aircraft.

See also https://modelengineeringwebsite.com/Chenery_drawings.html