Horrid Henry is written by Francesca Simon and there are a whole series of books available as well as also films, books on cd and it also available on CITV.

Horrid Henry is a modern version of Just William and features Horrid Henry who is a basically a boy who does everything he shouldn't and his little Brother perfect Peter.
Horrid Henry's underpants:

In this story Henry's Aunt send him some pants for his birthday the only problem is she thinks he is a girl and send him frilly pink pants! One day running late Henry accidentally puts the pink frilly knickers on!
The story focuses on how Henry tries to get rid of the knickers and how will he survive the school day without his friends finding out that he has girls knickers on. The adventures Henry has whilst wearing these are very funny and it really carries the reader along.

Recommendation
I have listened to this on story Cd and it was very funny proving a hit with both my girls and indeed this has sparked a love of Horrid Henry the eldest loves reading these books. I personally think these are brilliant as they are very funny and in my experience the children in my daughter's class aged between 5 and 6 are desperate to find out more about his adventures.

Cost and stockist
This book is available from Amazon at £ 3.24 or it is also available as an early reader which has larger print at £ 2.99 www.amazon.co.uk I would also suggest having a look in your £1 shop if you have one as I picked up a couple in my local branch.

My 6 year olds comments.
I like this story because it is very funny Henry is very silly and I like it when he has Pea ns when the teacher finds the knickers and shows the class I think both boys and girls will like this story.