This impressive looking aircraft was the answer of the de Havilland company to an British Air Ministry early 1920s requirement for an experimental cantilever monoplane to be powered by the promising Napier Lyon engine. Two of them were completed in 1921-22 and both underwent tests to explore in UK the commercial possibilities of a formula already explored with success by Fokker. It was not to be. The technically conservative British were not interested in daring steps then.
With that ungainly undercarriage chassis the Doncaster remains me one of those ancient tin aircraft toys.