Harry Potter paintings for auction

The Thomas Taylor watercolour may fetch £25,000

Two original illustrations for the first Harry Potter book are to go on sale at Sotheby's auction house in London on 10 July.

The watercolour of Potter himself is expected to fetch between £20,000 and £25,000.

The images, by Thomas Taylor, were reproduced on the cover of Harry Potter And The Philosopher's Stone and have set the look of the character ever since.

Book covers set the look of Potter from the outset

In a recent interview author JK Rowling said of Potter: "Most people's idea of him comes from the different book covers - and they're not changing."

The illustration of Harry Potter standing by the Hogwarts Express is a signed watercolour.

The other illustration, also a signed watercolour, is of Potter's mentor, Professor Albus Dumbledore.

Meanwhile, Harry Potter creator J K Rowling is to take part in an exclusive documentary for BBC One later this year.

In the hour long programme, she will talk in detail for the first time about the inspirations for Potter, and her experience of writing the series.

BBC One's boss Lorraine Heggessey said: "I'm delighted that this year, BBC viewers can enjoy discovering more about the world of Harry and his friends."

J K Rowling has never taken part in a major documentary before, though the Harry Potter books have already sold more than one hundred million copies across the world.

A new trailer for the movie generated huge interest when it was release on the internet and in cinemas last week.

The two-and-a-half-minute sneak preview gave fans of the book the first chance to see many of the scenes that will appear in the film version which is set for release in November.