As the frenzied scenes that greeted the publication of his final adventure proved, millions are addicted to Harry Potter.

Now a psychologist has claimed that many of the boy wizard's readers are suffering from withdrawal in just the way that drug addicts do.

Jeffrey Rudski says he found symptoms including depression, loss of appetite and sleeplessness among ten per cent of the 4,000 Potter fans he studied.

At least 10 per cent of fans are suffering from withdrawal
since publication of the seventh and final book

A further 20 per cent admitted being on the verge of addiction to J K Rowling's creation. With nearly 400,000,000 copies of the seven-book series sold worldwide, that means the numbers affected could run to millions.