Conservationists at England's only wild beaver colony denied that a European beaver which has set up home on the Thames is a fugitive from their estate.
Experts say the mysterious arrival is from a new source of beavers, and not one of the six introduced three years ago to the Lower Mill Estate - a luxury waterside housing development in Gloucestershire.
The estate says the rodent is not one of theirs but has offered its skills to help catch it. Dr Simon Pickering, Cotswold Water Park director of conservation, said: "It's not from Lower Mill Estate as far as we're concerned. It has probably come from a zoo or a small private collection, but its difficult to say."