A Sussex artist's illustrations for the front cover of a Harry Potter book failed to reach the expected asking price at auction last night.

Three original watercolours by Newhaven artist Cliff Wright from the cover of Harry Potter And The Chamber Of Secrets went under the hammer at Christie's.

The original design for the front cover of the book was expected to fetch £30,000 but remained unsold.

Two illustrations which featured Harry in a blue Ford Anglia and the Hogwarts School of Witchcraft and Wizardry fetched £12,000 and £4,000 respectively. Both amounts were the minimum asking price.

The successful and bespectacled bidder, who bore a striking resemblance to Harry Potter, hailed from Peter Harrington's antiquarian booksellers in Fulham.

He said: "This artwork fetches this kind of money because of the popularity of the books. I'm confident I'll be able to sell these paintings because of everything that's happening with Harry Potter. And it will probably go to a British buyer."

The disappointing sale price came despite the fact that Pottermania shows no sign of waning.

The eagerly-awaited film, Harry Potter And The Philosopher's Stone, opened last month and is predicted to become one of the biggest-grossing movies of all time.

Before the sale, Hayden Pyle, Christie's book illustration specialist, said: "In terms of Harry Potter book covers, only one has come up for sale so far. That was the cover of the first book, which made more than £85,000.

"Despite the fact the Harry Potter connection undoubtedly increases their market value, these works are, on their own merits, wonderful watercolours.

"If you take into account how popular Harry Potter is at the moment, the timing could not be better."

The paintings, created in 1997, were the highlight of an auction of original book illustrations which included artwork from the Winnie The Pooh series.