Children visiting the Tower of London risk having swear words croaked at them by the resident ravens, the Beefeater in charge of them has said.

Christopher Skaife, who has been the Ravenmaster at the Tower for seven years, said the birds are misunderstood, but intelligent – and have learned how to use bad language.

In a new book, The Ravenmaster: My Life With The Ravens At The Tower Of London, Mr Skaife tells how the famous black birds are fed mice, rats and day-old chicks, and play games such as Kerplunk with their guardian and friend in exchange for their favourite foods.

His favourite bird, 12-year-old Merlina, has become adept at using her beak to mimic noises and talk to him, he said.

He explained: "Merlina likes playing with sticks while rolling on her back and doing forward-rolls. She is also adept at mimicking strange sounds to get what she wants.