The Harrier, like another recently retired aircraft, Concorde, is an indication of how advanced aircraft design was in the fifties. Although the Harrier has in recent years become an American aircraft it was in fact developed by Hawkers as a private venture, - the P1127. The British Government, not having the foresight to appreciate its potential, would have had it cancelled under the policies of the 1957 Defence White Paper. The defence cuts which saw the demise of the Hawker P1083 and 1121, the Vickers-Supermarine Type 545, the Avro Type 720 and my favourite, the Saunders Roe SR177 were based on the false premise that missiles were the only airborne weapons needed for future warfare.
The P1127 became an official M o A order in 1959, the protoype flew in November 1960, and it put Britains years ahead of the rest of the world.
By 1963 it was under threat from the politicians, and only missed being cancelled because it was so far advanced that it was cheaper to put it into production.
Regards Dave