The superlative Harrier jump jet remains the only V/STOL fighter to have served successfully with any of the world's air forces. Developed through numerous variants, it saw 40 years of service with the RAF before its premature retirement in 2010. It continues to fly with the US Marine Corps - as well as the navies of Italy and Spain - as the AV-8B The Harrier was developed into two distinct types: the original British GR1/GR3/AV-8A/Sea Hunter and the later composite AV-8B Harrier II. The author Denis J. Calvert is one of Classic Aircraft magazine's longest serving editorial contributors. He is an authority on the Harrier and as a specialist aviation journalist he has followed its career for over 40 years.