Nobody would ever have known: he took a handful, and left several million behind. But on Monday Ian McEwan confessed to Andrew Marr on Radio 4's Start the Week that he had taken a few pebbles from the Dorset coastline which inspired his latest book, and kept them on his desk as he wrote On Chesil Beach.

If he had confessed to loading one of the sarsen boulders from Stonehenge into his car boot, the response could hardly have been more ferocious.

Chesil Beach, a 22-mile natural wonder where storms grade the stones by size, is a site of special scientific interest. Among cries of outrage from conservationists, Weymouth and Portland borough council "invited" him to return the stones. Invited as in "or face a £2,000 fine".

McEwan was too busy to take them back in person but entrusted them to a film crew visiting his home, and yesterday the pebbles were returned. "I was not aware of having committed a crime," he said. "Chesil Beach is beautiful and I'm delighted to return the shingle to it."