Without knowing who has created the works, people can bid for them on eBay until the auction, called The Big Art Secret, closes on Sunday. Proceeds from the sale will go to St Wilfrid's Hospice. Hockney's work is "an ink and colour crayon drawing on a postcard" and Emin has donated four postcards.
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Today is World Book Day which promotes reading. We asked you to send in your photos and here are some of the best.
Her partner was upstairs at the house at Basildon in Essex getting her hospital bag when the masked gang smashed their way in using crowbars
The Rail Minister said it was not a matter of crowd control but passengers "trying to get home after a long day at work".