Speculation was rife yesterday afternoon when a huge bang was heard across south east London and Kent.

News Shopper was inundated with phone calls and e-mails from concerned residents after the bang was heard at 4.44pm, with theories including a blown up substation in Petts Wood, an explosion in Farnborough and even aliens landing near Swanley.

The bang was heard across Bromley, Bexley, Dartford and Gravesend, with many taking to Twitter and Facebook to express their concern.

Christine Hayes got in touch to say: "Heard terrible noise, house seemed to shake reminded me of when 80 foot beach tree hit house in storm of 1987.

"Looked out in garden but could see nothing.

"This was around 4.45-5pm in Tower Road, Orpington."

Mike Haley said: "Was heard in St Paul's Cray and Bexley, we thought it was a firework going off our cat went mad, daughter was bringing in horses at work and had them rearing and galloping off." 

And Pamela Webster added: "Approx 4.30pm at home in Crockenhill, near Swanley, heard what seemed like a loud crash of something landing on the roof of my bungalow and a vibration.

"There was no sound of planes overhead or traffic outside.

"I investigated some minutes later but nothing was seen. Could it be aliens getting ready for a Halloween intrusion."

News Shopper was the first to solve the mystery when we tracked down RAF Wing Commander Martin Tinworth, who confirmed the sound was the sonic boom of two Typhoons launched from RAF Coningsby in Lincolnshire.

The Typhoons were scrambled to intercept an Antonov-An 26, which had lost contact with air traffic control.

The Russian-built Latvian cargo aircraft was escorted to Stansted Airport.

An unofficial Twitter account linked to RAF Coningsby claimed threats were made to shoot down the plane if it did not respond to orders.

Listen to the audio of the sonic boom here: