Notable as the first aero engine to be designed by Geoffrey de Havilland it was produced in small numbers between 1909 and 1910 by Iris Cars Ltd of Willesden from which it took its name.

He had studied the engine used by the Wright brothers and believed that he could design a similar unit with an improved power-to-weight ratio.

[1] The design featured a horizontally opposed, four-cylinder layout with a single camshaft operating poppet valves through pushrods that were hollowed to save weight.

[2] In 1957 instructors and apprentices from the de Havilland Aircraft Company Technical School decided to construct a replica engine, almost 50 years after the original Iris was built.

The Iris Motor Company had long since closed and its records, along with the original engine drawings, were destroyed by German bombing during World War II.