Rowling discusses her creation with Lisa Simpson

Rowling will meet up with Homer and his family for a special episode of the animated series set in London, the writer's publicist has confirmed.

Bart's sister Lisa turns out to be a big fan of the Potter books and discusses Harry with Rowling.

Rowling has already recorded the episode.

Don Payne, executive producer of the cult US cartoon, told The Sun newspaper: "The Simpsons bump into JK Rowling outside a bookshop and they talk all about Harry Potter."

He added: "We're very excited about the episode and rest assured every British clich� will be trotted out to get a laugh."

Lord of the Rings star Sir Ian McKellen also reportedly appears in the episode.

He is hit by falling scaffolding and struck by lightning, according to The Sun.

It says the Simpsons watch him perform on stage in Macbeth but bring him bad luck by saying the play's name aloud - a theatrical superstition.

Simpsons creator Matt Groening reportedly wants Prime Minister Tony Blair to provide his own voice for the episode.

The plot is said to revolve around Homer bringing Marge and the family to England to find a woman with whom Grandpa had a relationship during the war.