1, WHEN Arthur Weasley takes Harry and his pals to the Ministry of Magic they must first dial a secret code into a telephone keypad. He enters the number 62442. The letters underneath those numbers on a standard mobile phone spell out the word "magic".
2, IF a muggle spotted Hogwarts, they would just see an old ruin with a sign "Keep out, dangerous building".
3, NATALIE McDonald, who appears on page 159 of Harry Potter And The Goblet Of Fire, was a real person.
She was a nine-year-old girl from Toronto, Canada, who was dying of leukaemia. She wrote to JK Rowling asking what was going to happen in the next Harry Potter book as she would not live long enough to read it.
The kindly author emailed back, but Natalie had died a day earlier. In tribute, she became a first-year student at Hogwarts named by the Sorting Hat in Gryffindor - the house for the brave at heart - in the fourth book. When Rowling was later in Canada for a promotional tour she visited the McDonald family.
4, LORD Voldemort is definitely NOT Harry's dad. Rowling has a retort for anyone who develops this theory: "You lot have been watching much too much Star Wars."
5, HERMIONE'S Patronus is an otter because JK Rowling likes otters and sees herself in Hermione.
6, ROWLING named the driver and conductor of the Knight Bus after her grandfathers, Ernie and Stanley.
7, WIZARDS find garden gnomes a pest because they eat the roots of plants, and, like moles, make little piles of earth.
8, QUIDDITCH started in the 11th century at a place called Queerditch Marsh, which is not marked on muggle maps because wizards have made the place unplottable. Originally it was quite a crude game played on broomsticks with just the quaffle.
9, TWIN jokers Fred and George, the owners of Diagon Alley's new Weasleys' Wizard Wheezes, celebrate their birthday on the stupidest day of the year, April Fool's Day.
10, SIRIUS Black is named after the brightest star in the night's sky, also known as the Dog Star. This is very apt since when Sirius used his skills as an animagus he turns into a big black dog.
