Top-secret Amazon drone filmed zooming through the air above Cambridgeshire testing facility

The facility is closely guarded to stop anyone sneaking a peek at the experimental craft.

Photographer Dean Cranston said locals had become increasingly intrigued by what was happening on the field, which sits about 10 miles south of Cambridge.

He and two other photographers decided to check out the site after locals became worried and curious about what was happening – but they were confronted by unhappy security.

He said residents had been baffled by the “cloak and dagger” activities.

Speaking to the Sun Online, he said: “Amazon is obviously ploughing tens of millions of dollars into the future of how to deliver parcels.

“They have basically hired a farmer’s field in Cambridge, taking it over and doing something there on the land.”

He said security armed with ear pieces, binoculars and radios monitored the site constantly, ensuring anyone from the public did not venture off a nature path onto the field.

He said: “They won’t identify themselves, they won’t confirm or deny anything.

“It’s very peculiar.”

He said some locals had even speculated that there were “UFOs” at the site so he decided to video their discussions with security.

But while visiting the field on Thursday, he said the group had been confronted by men, including one with a scarf over his face, who insisted they leave.

Refusing to confirm if they were security, the men were recorded by the savvy photographers who demanded to know why they were being made to move on.

It was only once another security guard appeared – having been radioed in – and ashowed his identification that the photographers agreed to leave.

Mr Cranston said: “It felt really hostile, like some kind of cult.

“You wouldn’t believe what’s going on there… we were told by locals that there was a lot of strange behaviour going on.”