In the winter of 1946, Britain was perhaps six months away from becoming the first nation to fly faster than sound. In a guarded hangar sat a small, bullet-shaped jet called the Miles M.52, all but finished, its test pilot chosen, its supersonic trials pencilled in for that October. And then, with a single order, the government cancelled it.

Eighteen months later it was an American, Chuck Yeager, who broke the sound barrier in the rocket-powered Bell X-1 — and the honour Britain had been chasing was gone for good. The story of the M.52 is one of dazzling engineering, official timidity, and one of the most bitterly debated decisions in British aviation history.

What makes it sting is that the M.52 would almost certainly have worked. We know, because a model of it later did exactly what the aircraft was designed to do.

The 1,000 mph secret

In December 1943, at the height of the war, the Air Ministry handed a top-secret contract to Miles Aircraft — a small firm known for clever thinking — to build the world’s first piloted aircraft capable of 1,000 mph. The engine would come from Frank Whittle’s Power Jets. With almost no data on how anything behaved beyond the speed of sound, Miles turned to an unlikely source: wind-tunnel tests on rifle bullets and artillery shells. From that they shaped a needle-nosed aircraft with a razor-thin wing.

A decade ahead of its time

The M.52 bristled with ideas that would define supersonic flight for decades. Its wings were extraordinarily thin and sharp-edged. Its pilot sat in a jettisonable, pressurised nose cone that could be blown clear in an emergency. And most important of all, it had an all-moving tailplane — the entire horizontal tail pivoted as one surface, the single most important control breakthrough for staying flyable as an aircraft approaches the speed of sound. In the summer of 1944, controversially, all of this research was handed to the Americans.

The cancellation that still baffles

By early 1946 the first M.52 was all but built and the Fleet Air Arm’s Captain Eric “Winkle” Brown — the most experienced test pilot in Britain — had been named to fly it. Then, on 12 February 1946, Miles was ordered to stop. Officials cited cost and doubts that supersonic flight was even achievable soon. To the men who had built it, the decision was incomprehensible.

America breaks the barrier instead

The glory went across the Atlantic. On 14 October 1947, US Air Force Captain Chuck Yeager rode the rocket-powered Bell X-1 past Mach 1 — and, tellingly, the X-1 used an all-moving tailplane of the kind the M.52 had pioneered, after the Americans had been given Britain’s research. How much that transfer mattered is still argued over, but the timing has never sat comfortably with British engineers.

Proven right — too late

Britain did not entirely abandon the design. Engineers built unmanned, rocket-powered scale models of the M.52 and air-launched them from a Mosquito. On 10 October 1948, one of them held Mach 1.38 in stable, level flight — doing precisely what the full-sized aircraft had been built to do, and proving beyond doubt that the M.52 concept was sound. By then it was a footnote. The aircraft that could have made Britain first through the sound barrier had been scrapped, and its designers were left to wonder what might have been.

Sources: The History Press (“Captain Eric ‘Winkle’ Brown & the gateway to supersonic flight”); Wikipedia (Miles M.52; Bell X-1); The Engineer. The degree to which M.52 research aided the Bell X-1 remains a matter of historical debate.