The bomb has been in the ground for almost 57 years
Tom Jones, 83, told parish councillors in the village of Sandhurst about the bomb when they announced plans to build a playground on an allotment.
He said he remembered a German bomb falling on the site in 1941.
His fears led to a survey and the discovery of the 500lb device, embedded vertically into rock more than three metres below the surface of the ground.
Army bomb disposal experts were called in and Mr Jones, a retired farm worker, pushed the detonation button early on Saturday afternoon.
Plume of smoke
Shortly after 1.30pm as the bomb, was detonated, a plume of black water mixed with earth and sand shot into the Gloucestershire sky.
As senior officer Major Tim Vaughan gave the all-clear after the blast, he said: "It is very hard to judge but the plume of water, steam and earth looked to rise 150-200ft into the air."
A 40-strong crowd waiting at the edge of a 500-metre exclusion zone, which had been thrown around the bomb site, heard a muffled bang before feeling the ground-shaking.
The explosion had been suppressed by submerging the device in 2 metres of water.
Night of attack
Mr Jones later described the night the stray bomb fell.
"Three bombs fell and two of them moved our bed across the room with the blast, but one did not go off.
"The next day I went to my allotment and there was a hole 18 inches round where the bomb had landed.
"I poked down the hole with a cane but could not touch it.
"People did not believe me but I knew it was there because I had heard the dull thud when it landed.
Around 250 residents had to leave their homes as the 1.2m long bomb was detonated.
Mr Jones said: "When I mentioned it from time to time over the years people said I was making it up or playing an April fool."
"I feel happy and pleased with myself. I can go through the village with my head up now."
Army spokeswoman Captain Rosie Stone said everything had gone to plan, and officers would be checking to ensure all material had been exploded.