A RETIRED teacher forgot to use the appliance of science when he took three weeks to tell police about a hand grenade dug up in his garden.

Dave Horrobin left the grenade at the bottom of his garden, then jetted off for a fortnight's holiday on Spain's Costa del Sol.

After finally ringing the police early yesterday morning, nearby houses were evacuated and a bomb disposal unit was called in to blow up the device.

Mr Horrobin - who taught science at Malvern's Dyson Perrins CE High School until five years ago - left the grenade because he presumed that, as it was old, it was safe.

His neighbour, pensioner Gerald James, found the grenade more than three weeks ago while helping Mr Horrobin to mend his fence.

He moved it to a nearby shrub, then told Mr Horrobin about it.

"I was very surprised," said Mr Horrobin, whose guest house at Picken End, Hanley Swan, near Malvern, did not have any customers at the time.

"I wondered how it got there and did not know what to do about it.

"There was no pin in it. I stupidly moved it round the back of the house to have a closer look, decided it was inactive, so put it down the garden.

"I'd been meaning to ring the police on various occasions but never got round to it. I gave police a ring, they came here and decided it could be live and cause problems.

"They said the bomb squad needed to be called in."

With the fire service and ambulance on standby, the bomb disposal unit built a three-ft high wall of sandbags around the grenade and blew it up yesterday.

"We decided Mr James should blow it up as he found it," said Mr Horrobin. "The explosion was a generous one and left a big hole a couple of feet deep and wide."

Mr James said the area had never been so busy.

"I was honoured to press the button to blow it up," he said.

The Ministry of Defence said anyone finding an explosive device should call police immediately.

"They can then investigate whether it is live and how they can dispose of it," said Ministry of defence spokesman Gemma Blackburn. "People should contact them as soon as possible."