Most gardeners pride themselves on knowing their onions, but Ignatius Stewart appears to know his bombs too.

He was digging up roots in his allotment in Leyes Road, Custom House when he came across something that baffled him.

It was a metal and concrete object and although he spent several days digging around it he, and his fellow gardeners, still couldn’t figure out what it was.

He was convinced that it wasn’t a bomb. Mr Stewart, who lives in Victoria Dock, said: “I thought it was a mechanism, I could get to it but it was much deeper than it looked. It looked like it was man-made. There was metal on top and there was what looked like brickwork underneath. There was a steel pipe that was attached and the end was covered.

“It was about 18 inches circumference and about a foot deep. I dug all the way around it and exposed most of it. I could see there were things that were attached to it. There was some mechanical works attached, like pipework.”

Eventually Mr Stewart contacted Newham Council with the result that the emergency services were called and roads around the area closed off as a precaution in case it was an unexploded World War Two bomb.

Specialist officers who inspected the device established it wasn’t explosive.

A spokeswoman for the police said the device was a concrete plug with a metal attachment.

She said Mr Stewart had done the right thing in alerting the authorities even though it was subsquently found not to be an explosive device. She urged people not to dig up such devices in case they prove to be explosive. They should contact the emergency services, she said.