BBC News Online: Entertainment

Potter magic helps charity

She has also written Quidditch Through The Ages, a library book that Harry uses to learn the rules of the school's signature sporting activity, which involves teams playing ball on broomsticks.

"When Comic Relief asked me to write something I thought I would just love to write the two books," Ms Rowling told the BBC.

"I did two because I had two in my head and I couldn't really decide between Quidditch and Fantastic Beasts, so I decided to do them both."

The Edinburgh-based single mother - whose first name is Joanne - has sold more than 30 million copies of her schoolboy wizard books worldwide.

Comic Relief founder Richard Curtis approached Rowling to write a story saying he was sure she would not be able to but he would still love her books regardless.

"It was a very clever way of asking somebody to do something, though I didn't really need much persuading" Rowling told the BBC.

Top tips

And Bridget Jones author Helen Fielding has been called upon to write Bridget Jones Guide to Life for the charity event.

The book offers Jones' top tips on how to give the perfect dinner party, handle all accounting and never put on a pound in weight.

Ms Fielding, whose first book Cause Celebre featured aid workers in Africa, was keen to help Comic Relief.

"I was honoured. I have been more than lucky with Bridget and was more than pleased to help."

A Bridget Jones movie starring Renee Zellweger as the hapless Miss Jones is due for release next month.

The books will be sold for £2.50 and £2.00 of the profit will go to charitable projects at home and abroad to coincide with Red Nose Day on 16 March.