It was designed to test the idea of "slip-wings", where the aircraft could take off as a biplane, jettison the upper, disposable wing, and continue flying as a monoplane.

Amongst the proponents of the "slip-wing" was Noel Pemberton Billing, the founder of Supermarine, who wrote several articles in the aviation press promoting the idea, either with a manned, reusable auxiliary wing, or a disposable or "scrap-wing".

While the proposal was not accepted by the Air Ministry, Hills and Sons decided to continue with the project as a private venture, and so built a scale test-bed, to prove the slip-wing process.

[1][3] The test bed, known as the Bi-mono, was a small tractor monoplane with a fabric-covered steel-tube construction fuselage and a wooden wing.

[5] The test proved successful, with no great change in trim and a few hundred feet in altitude being lost when the upper wing was jettisoned.