The bomb squad was scrambled to Biggin Hill after a resident dug up a “suspicious object” at the bottom of his garden.
Specialist officers rushed to an address on Kings Road on Sunday and quickly shut off the road and told people to stay indoors.
They were called after Nick Kent, 55, phoned his local police station with concerns after he stumbled across the item while doing some gardening.
Police visited Mr Kent and took pictures of the item - they then sent them onto the bomb disposal team two experts were put into action.
Mr Kent said: “The police sent some people round to take pictures. The next thing I know the bomb team came and shut off the whole road.
“They took it away – I couldn’t tell what it was.
“Living in Biggin Hill I thought it could be something interesting, but I didn’t want to start digging it up.”
The electronic engineer had been laying some new turf when he made the discovery, which actually turned out to be some sort of pump.
Mr Kent thinks it could have fallen off a plane as Biggin Hill Airport used to be a major base for the RAF - and played a crucial role in The Battle of Britain.
The police reported: “We were called at approximately 10.45 to an address in Kings Road, Biggin Hill, after a suspected bomb was dug up in a garden.
“Cordons were put in place and a residents in the area advised to remain indoors before the suspect item was declared safe and cordons lifted at 1pm.
“The suspect item was an old metal pump.”