A gardener sparked a three-hour security alert when he struck metal while digging in his garden and feared it was a wartime bomb.

Roads were sealed off, a 200-yard zone of homes evacuated, a petrol station closed and the emergency ordnance squad called in before the bomb was identified - as a rusty water tank.

The drama began at 12.15pm on Thursday when retired pharmacist Trevor Staley, 56, of Amberley Road, Storrington, was working in his garden.

He said: "I was digging out the roots of an old laurel tree when my spade hit something that sounded heavy and metallic.

"It revealed the end of a cylinder with metal rivets surrounding a central core about 18in in diameter.

"I was a little concerned so I phoned the police and they called the bomb disposal people."

Mr Staley was told to stay away from his home as the team dug around the device.

He said: "They dug down the other side and realised it was a water tank of some kind. It's still under the tree now."

A police spokesman said: "You can never be too careful in a situation of this sort."

Mr Staley said: "It won't make me too popular with the neighbours."