They never recovered the body of Amy Johnson. Her aircraft was seen to ditch into the Thames estuary on a cold, foggy morning in January 1941, and the wreckage was located easily. But although they searched and searched, Amy herself was never found.
Eleven years before, when Amy was 27, her 19-day solo flight from London to Australia had captured the imagination of the world, and exciting tales of flying blind through desert sandstorms, and forced landings where she had patched her aircraft's wings with sticking plaster, were sufficient to ensure an international celebrity. But one of Amy Johnson's claims was treated sceptically: she had, she said, a sixth sense by which she could navigate without a compass.
Now it is well known that certain birds and animals can use the Earth's magnetic field to navigate. Pigeons are the most notable example, but up to 60 other species with the same gift have been identified. Some large fish, for example, appear to detect the Earth's magnetic field by using electrical sensors in their snouts called, rather quaintly, the ampullae of Lorenzini .
In other species it is believed that pigments in the eyes become slightly magnetic when exposed to light, and under the influence of the Earth's magnetic field they alter the optical signals transmitted to the brain. Other creatures still have tiny crystals of an iron oxide, magnetite, embedded in their brains; these, rather like iron filings near a magnet, orientate themselves in the direction of the magnetic force. But Amy Johnson? Surely not!
But then in 1989 researchers discovered tiny crystals of magnetite in the human brain, and this prompted Dr Robin Baker of the University of Manchester to carry out investigations. His research, in its simplest form, consisted of driving blindfolded volunteers to unfamiliar locations; he found that, still blindfolded, some of them could indicate their direction relative to home, but that when magnets had been placed close to their heads, they could not do so.
Other research has revealed some interesting variations with regard to age and sex. This intuitive sense of direction, sometimes called magneto-reception is found to be particularly strong in some female subjects, developing gradually from the age of about nine, reaching a plateau of ability at 18, and persisting until its decline after the age of 40. By contrast, those males who possess the gift have only a relatively short interlude in life when it is in evidence, and even then it is much weaker than in females.
So perhaps, after all, the legendary and unbelieved assertions of poor Amy Johnson were correct.