The de Havilland Aircraft Company Limited was a British aviation manufacturer established in late 1920 by Geoffrey de Havilland at Stag Lane Aerodrome Edgware on the outskirts of north London. Operations were later moved to Hatfield in Hertfordshire.
Known for its innovation, de Havilland was responsible for a number of important aircraft, including the Moth biplane which revolutionised general aviation in the 1920s; the 1930s Fox Moth, the first commercial transport able to operate without government subsidy; the wooden World War II Mosquito multirole aircraft; and the passenger jet service pioneering Comet.
The de Havilland DH 106 Comet was the world's first commercial jet airliner. Developed and manufactured by de Havilland at its Hatfield Aerodrome in Hertfordshire, United Kingdom, the Comet 1 prototype first flew in 1949.
It featured an aerodynamically clean design with four de Havilland Ghost turbojet engines buried in the wing roots, a pressurised cabin, and large square windows. For the era, it offered a relatively quiet, comfortable passenger cabin and was commercially promising at its debut in 1952.
According to en.wikipedia