The Black Arrow First Stage is a medium first stage rocket. It forms part of the Black Arrow rocket and it can go 76% to orbit on its own. It is very similar to the Ariane 5 First Stage in terms of its lifting power and its fuel capacity, although it's cheaper than the Ariane 5 in Career missions.
Developed from the Black Knight missile, it was conceived after the Royal Aircraft Establishment proposed for a rocket capable of placing a 317-pound (144 kg) payload into Low Earth Orbit.
The program was authorized in the Fall of 1964 by Conservative Aviation Minister Julian Amery but the program was put to a hold when the incoming labor government decided to place the program on hold to reduce expenditure. In the following election, the government approved the continuation of the program but reduced the amount of planned launches from five to three. Four launches were eventually decided upon and it was only on its 4th launch that it had success.
As of 2018, the United Kingdom is the only country to have successfully developed and then abandoned a satellite launch capability.