Speaking to the BBC News website, Karyn Leadbetter, the shop manager, described the look of fear on her assistant's face when she made the unexpected discovery.
"She was looking through a box full of bric-a-brac when suddenly she shouted 'We've got a grenade and it's got a pin in it'.
"I said 'You're having me on', but when I saw it the colour drained from my face because I thought it could blow at any time."
The shop was evacuated and an army bomb disposal unit established that the device had been deactivated.
Leadbetter described it as a "terrifying" incident and requested that members of the public refrain from donating grenades or "anything that could cause alarm" in future.
Hampshire resident Sandra Buckland got more than she bargained for in a different sense after a visit to her local charity shop.
The Daily Mirror reported that Buckland bought the plate for £1 three years ago, but she recently saw a picture of it in a magazine and contacted an auction house. It transpired that the plate originated from the world-famous manufacturer Poole Pottery in the 60s, and she sold it for £1,760.
The Sun traced "the face behind the buns" who bared all for the British Heart Foundation poster to promote its 30 A Day exercise campaign.
The model, Charlie Street, 55, from south London, revealed that the shoot was far from glamorous. "I wish it had been in the Caribbean rather than on the south coast of Britain," he said. "I thought it was strange that I had to be photographed nude, but I wasn't going to make a song and dance about it because it was for a good cause."