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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Wednesday Evening's Pollen Forecast
Wednesday night's weather for the west of the region
Wednesday night's weather for the east of the region