[PAR] [TLE] Alan Samuel Butler [SEP] Alan Butler (22 November 1898 —24 May 1987), full name Alan Samuel Butler, was (claimed his obituary in "The Times") the first private aeroplane owner-driver.  From 1923 Butler was chairman of De Havilland Aircraft Company —which he financed— until 1950, a year when De Havilland employed 20,000 people and was building Comet, the world's first commercial jet airliner. [PAR] [TLE] De Havilland Comet [SEP] The de Havilland DH 106 Comet was the world's first commercial jetliner.  Developed and manufactured by de Havilland at its Hatfield Aerodrome, Hertfordshire, United Kingdom headquarters, the Comet 1 prototype first flew on 27 July 1949.  It featured an aerodynamically clean design with four de Havilland Ghost turbojet engines buried in the wings, a pressurised fuselage, and large square windows.  For the era, it offered a relatively quiet, comfortable passenger cabin and showed signs of being a commercial success at its 1952 debut.
[PAR] [TLE] Alan Samuel Butler [ SEP ] Alan Butler ( 22 November 1898 —24 May 1987 ) , full name Alan Samuel Butler , was ( claimed his obituary in " The Times " ) the first private aeroplane owner - driver . From 1923 Butler was chairman of De Havilland Aircraft Company —which he financed— until 1950 , a year when De Havilland employed 20,000 people and was building Comet , the world 's first commercial jet airliner . [PAR] [TLE] De Havilland Comet [ SEP ] The de Havilland DH 106 Comet was the world 's first commercial jetliner . Developed and manufactured by de Havilland at its Hatfield Aerodrome , Hertfordshire , United Kingdom headquarters , the Comet 1 prototype first flew on 27 July 1949 . It featured an aerodynamically clean design with four de Havilland Ghost turbojet engines buried in the wings , a pressurised fuselage , and large square windows . For the era , it offered a relatively quiet , comfortable passenger cabin and showed signs of being a commercial success at its 1952 debut .
In which county are the headquarters of this company located that developed one of the world's first commercial jet airliners built by Alan Samuel Butler?
In which county are the headquarters of this company located that developed one of the world 's first commercial jet airliners built by Alan Samuel Butler ?
Hertfordshire
Hertfordshire