A family of swans have been killed in air gun attack, the RSPCA have said, as a veterinary sanctuary trustee believes that the birds are targeted because they are a “symbol of the Establishment”.

The bodies of five cygnets and both of their parents were discovered wrapped in plastic bags after they were thrown down the bank of a stream in the Kent village of Benenden.

Kent Police were called to the scene last Sunday and the RSPCA has launched an investigation after X-ray images revealed one of the birds was peppered with pellets or shot.

Stephen Knight, a trustee of the Swan Sanctuary in Shepperton, Middlesex, said the royal birds are targeted in such attacks because of their relation to the Queen, who owns all the unmarked swans in England and Wales that swim in open water.

Mr Knight said: “The reason they pick on swans is because it is widely know that they belong to the Crown, so they are a symbol of the Establishment.