The Ministry of Defense said a Typhoon jet from RAF Coningsby in Lincolnshire was launched when communication was lost with a Heathrow-bound plane. It is understood the plane, travelling from the USA, landed without incident.
Most of the people who rang said they'd never heard anything so loud in their lives.
One man reported the noise from as far away as St Ives, on the far westerntip of Cornwall. He thought something had hit his roof because the whole house shook. The noise was so loud another person thought his neighbor's house had blown up. As an aside, I love St.Ives. All my books are written about St.Ives and Cornwall. In the futuriscic, fantasy adventure series, the characters call the place Saint Eyes.
When an aircraft approaches the speed of sound (768mph), the air in front of the nose of the plane builds up a pressure front because it has "nowhere to escape", Dr Jim Wild of Lancaster University explained to the BBC.
A sonic boom happens when that air "escapes", creating a ripple effect which can be heard on the ground as a loud thunderclap.
It can be heard over such a large area because it moves with the plane, rather like the wake on the bow of a ship spreading out behind the vessel.
I can't believe the pilots would have deliberately caused this effect on the population below. Perhaps it happened accidently, although I wouldn't have thought this was possible with all the gismos available in a jet liner. Let's hope an inquiry is held to establish the cause.