The Harrier GR1 has been considerably developed since entering service with RAF No.1 Squadron in April 1969. The Sea Harrier entered service with the Royal Navy in 1979, and played a large part in the 1982 Falklands conflict. Harriers are also in service with the United States Marine Corps and the Spanish and Italian forces. This is a history of the aircraft, much of it contributed by Duncan Simpson, the Harrier"s Chief Test Pilot.