When Barney met Mabel, there was an instant and fatal chemical reaction.
On Tuesday night the doberman pinscher guard dog, after six years' blameless service, went berserk: within minutes Mabel, a 1909 German-made Steiff teddy bear once owned by Elvis Presley, more recently the pride and joy of an English aristocrat, lay mortally wounded.
Barney went on to rampage through hundreds of rare teddies, all on loan to the Wookey Hole Caves tourist attraction in Somerset, southwest England, and so valuable that the insurers had insisted on a guard dog to protect the premises at night. The aftermath, according to shocked staff, was appalling: shattered limbs, gouged eyes, ears torn off and pools of sawdust everywhere.
"Up to 100 bears were involved in the massacre," Daniel Medley, general manager of Wookey Hole Caves, said on Tuesday night. "It was a dreadful scene."
Barney's mortified handler, Greg West, took 10 minutes to get the dog back under control.
"I still can't believe what happened," he said. "Either there was a rogue scent of some kind on Mabel which switched on Barney's deepest instincts, or it could have been jealousy: I was just stroking Mabel and saying what a nice little bear she was."
Mabel usually lives at Maunsel House, a 13th century manor house belonging to Sir Benjamin Slade.
Sir Benjamin, who inherited the estate in 1982, recently announced he was conducting a worldwide DNA search to find the closest heir to the estate: so far he has received over 15,000 claims, including one from a man currently residing in a New Delhi prison.
He collects Elvis Presley memorabilia, and bought the bear at a Memphis auction for ?40,000 (US$40,000).
Medley had the unenviable job of phoning him to explain, as well as he could.
"It was one of the most embarrassing experiences of my life. I had a very brief conversation with him, and it's fair to say he was not best pleased. He sent around one of his men this morning to collect the body," Medley said.
He is anticipating another very awkward conversation: dozens of the damaged bears belonged to another private collector, currently out of the country on holiday.
"I hope she doesn't read about it in the papers, or she'll be straight back on the next plane," he said.
Staff were still working last night to restore the display, which is expected to reopen this morning.
"We have asked the security firm not to send us that dog again," Medley said.