Hundreds of thousands of copies of the sixth wizardly adventure have been ordered, so the Post Office will need 150 more trucks than usual on 16 July.

Posties delivered 500,000 copies of the last book, and expect more this time.

The books are so heavy, some postmen might need extra help carrying them on their Saturday morning rounds.

But if you're worried they might not cope, don't panic.

Spokesman James Eadie said they had a "very carefully planned operation" set up.