The announcement has only deepened the mystery of what caused the noise which was felt along the East Coast from north of Whitby to south of Filey.

The Ministry of Defence denial means there could only be a handful of explanations for the boom.

It could have been caused by a meteorite, the wildest theory being aliens from outer space.

Experts at the British Geological Survey in Edinburgh said its instruments proved conclusively the noise in Scarborough on February 21 was not caused by an earthquake.

They said the most likely cause was a sonic boom, but did not know what had caused it.

The Ministry of Defence said in a letter to Evening News reporter Chris Nixon: “After a thorough investigation into this incident, the RAF Police concluded that military aircraft were not responsible for generating the noise you heard.

“Although a number of aircraft were operating in the area, radar evidence has shown that at no time did they operate at supersonic speeds.”

A sonic boom can occur when an aircraft breaks the sound barrier at supersonic speed during certain weather conditions.

The only civilian aircraft capable of supersonic speeds is Concorde – all the fleet has been grounded since the Paris air disaster in August last year, apart from a Concorde test flight from the French capital to the south of France.

Glen Ford, a seismologist at the British Geological Survey, said that on the day of the incident in Scarborough “a spurious signal” had been picked up on equipment in Leeds.

“We had an earthquake last Sunday in Dumfries in Galloway, but there has not been an earthquake in Scarborough,” said Mr Ford.

He said an earthquake was felt over a circular area. The incident in Scarborough was most likely a sonic boom because it was felt in a straight line down the coast, said Mr Ford.

“A pressure wave can travel great distances. In this case it seems to have gone across the North Sea and then smacked into the East Coast. Something definitely whacked the coastline.

“A sonic boom can be caused by a meteorite entering the earth’s atmosphere and in the past there have been reports of spectacular lights being seen on the north-east.

“In one case this affect was caused when a Russian satellite broke up and entered the atmosphere.

“On one occasion off Hartlepool there was a sonic boom caused by RAF Tornadoes exercising which caused buildings to be evacuated.”

The Evening News reported the same week as the apparent sonic boom that a meteorite shower was seen off the East Coast, but it seems we will never know for certain what caused Scarborough to “go bump in the day”, rather than “bump in the night.”