The most valuable G4 PowerBook in the world - signed by Sir Paul McCartney - is being auctioned to raise funds for a kidney dialysis ward for children in the North East of England.

Donated to the charity - the Alice Skinner Appeal - by Paul and Heather McCartney, the PowerBook was signed in LA in October 2002. The celebrity couple agreed to auction the item to help raise money for the appeal. As well as Sir Paul's signature, the PowerBook carries a £10,000 reserve price.

George Skinner, father of two-year old Alice, a little girl who has been on kidney dialysis since birth in 2001, explained: "My little girl was born with no kidneys and has been on dialysis since she was born. Paul and Heather agreed to help us. We are trying to gather £250,000 to finance a kidney dialysis ward for kids, as there isn't a dedicated ward for children suffering from this in the North East".

"We have raised £7,000 in six months and hope to raise more through this auction," he explained.

Some of the money raised through the auction for the PowerBook will be donated to the Alice Skinner Appeal, while some will go to the McCartney's chosen charity, the Adopt A Minefield Campaign.

A range of other autographed items are also available, including: signed football memorabilia, autographed books - even a bottle of House of Commons-branded eight-year old Malt whisky signed by Gordon Brown.