It was as an unemployed single mother living in an Edinburgh council flat that author JK Rowling first put pen to paper. And the chair in which she wrote the first two Harry Potter books has just sold for £20,000.

The chair was one of four mismatched dining room chairs given to Rowling author free of charge. As the most comfortable of the four this chair ended up being the one she sat in to write the first Harry Potter book in front of her typewriter.

It has now been transformed into a piece of literary memorabilia.

Rowling originally donated the chair to a charity auction called Chair-ish a Child where it realised £15,000 in aid of the NSPCC in 2002. But it has since been re-sold on eBay with 20% of the proceeds set aside for a charity which sends schoolbooks to disadvantaged children overseas.

Bidding started at one penny but the usual frenzy surrounding Harry Potter paraphernalia quickly saw the price rise to £19,555 at the hammer.

The Art dealer organising the sale was quoted as saying "It's a chair you would normally pay a tenner for in a junk shop but, historically, it's the most important chair in Muggeldom."

The chair is undoubtedly one of the most exceptional pieces of Harry Potter memorabilia offered for sale. Rowling had also decorated the chair including the words 'I wrote Harry Potter here'.

The chair also comes with additional provenance in the form of a special Owl Mail, signed by Rowling, addressed to 'the new owner of my chair' including the line "My nostalgic side is sad to see you go but my back isn't."

The Harry Potter series of books, and movies, have been a global phenomenon, the books alone selling over 400m copies.

The demographics behind the Harry Potter memorabilia market suggest that items are currently undervalued and will show their real potential when the young readers come of age and have a disposable income.