Fairey Delta 2
Dora Wings

This is a significant and very pretty aircraft. It was designed as a research aircraft to investigate delta wing behaviour at transonic speeds and a sleeker more capable follow-on to their Delta 1 (which had begun life with near-vertical ramp launching in mind). During testing it became clear that its performance was remarkably good, going supersonic without engaging reheat. Fairey were keen to make a World Airspeed Record attempt, but neither the UK government nor engine supplier Rolls Royce were supportive of the idea. In the end the Government agreed to loan Fairey one of the two prototypes for a limited period, providing Fairey paid for the use of any Royal Aircraft Establishment facilities and covered the cost of insurance. In March 1956 the Delta 2 become the first jet aircraft to exceed 1000 mph in level flight, clocking an official 2-way average speed of 1132 mph. This was 310 mph or 37% faster than the previous record held by a North American Super Sabre and the largest increase in the record at that time.
Much of the subsequent testing was undertaken in France, due to a ban on overland supersonic flights in the UK. There is speculation that the design of the Dassault Mirage may have been influenced by the Delta 2, but the UK Government's belief that anti-aircraft missiles would render fighters redundant meant no funding was provided to develop the fighter variants that Fairey proposed.
What did happen, though, is the very airframe that had taken the World Airspeed Record was extensively modified in 1961 to become the BAC 221 and successfully test the ogival delta wing proposed for the Anglo-French Concorde at high speed.