Black Arrow was a modification of the British Black Knight rocket and burnt 85% hydrogen peroxide (HTP) and kerosene. It stood 13m high and weighed 18 tonnes at takeoff. It was a 3 stage rocket capable of placing 100kg into earth orbit. It was launched 4 times, 2 successfully, and on its final flight in 1971 "Prospero" achieved earth orbit into a 531/1402 km orbit, where it still remains to this day, the first British Satellite to achieve orbit. The entire project cost just £9 million; which by space standards was a tiny, tiny cost, even in those days.

Interestingly, Black Arrow could have been fitted on top of Blue Arrow for much greater payload; and probably would have been quite capable of placing payloads into GEO. For £90 million a project could have achieved geosynchronous orbit; and that's probably just the development costs, each launch would have been cheaper.

However the GEO market did not exist in those days, and the program was cancelled as the government could not see the point, and lacked the finance to continue it.

Ironically, that market appeared just a few years later... and the French program that became Ariane were able capitalise on this crucial mistake.