It was a stifling evening in July and Matt Phelps was out for a stroll, when a piercing, whirring noise stopped him in his tracks. As an ecologist, Phelps knows his fauna – and he could think of no UK creature that could emit such a sound.

“It was like the classic sound effect of a cricket in a film, a beeping sort of little trilling sound,” said Phelps, who works at Knepp Estate in West Sussex. He returned with entomologist Graeme Lyons to track it down. But the sound, though incredibly loud, “seemed to be all around us … it was very ventriloquial”.

The duo hunted for three hours. Night fell before they realised their quarry was, said Phelps, “literally below the ground where we stood”.