The books sold for more than double their estimated price

Author JK Rowling signed and donated the seven books to raise money for Portobello Rugby Club in Edinburgh.

They were bought by an unnamed Scottish bidder, who said he would keep the novels as an investment.

Auctioneer Lyon and Turnbull had originally estimated the books would fetch about £3,000.

The funds will be put towards rebuilding the rugby club, which lost its archives when it was burned down by vandals last May.

Club president Iain Goodall said Ms Rowling donated the books after hearing about the fire through a friend who is a member of the rugby club committee.

As far as we know, no one has ever sold a full set of signed Harry Potter books Philip Gregory Lyon and Turnbull

He said that the size of the winning bid was an "unexpected windfall" for the rugby club, which will now be able to rebuild itself.

Mr Goodall added: "We lost everything in the fire. All the memorabilia since the club was formed in 1930 was lost.

"We only had two photographs remaining - one from 1931 and one from 1967. Every trophy, every plaque we had is gone.

"I'm so delighted at this unexpected windfall that we've received, thanks to the generosity of JK Rowling. We're starting again, like a phoenix rising from the ashes."

Philip Gregory, from the Edinburgh-based auction house, said the set of books was unique.

First edition

He said: "It is rare to have such a set of books appear at auction. As far as we know, no one has ever sold a full set of signed Harry Potter books.

"As there was no precedent, to put a price on this was extremely difficult but I'm delighted and over the moon with the end result."

Last year, 19-year-old Toby Rundle from Somerset sold a rare first edition of the original Harry Potter book, Harry Potter And The Philosopher's Stone, for £7,200 to fund his university degree.

Mr Gregory said that the result was testimony to the continuing popularity of Ms Rowling's work.

He said: "If it had been any other author, it wouldn't have caught the imagination of the public."