Coldplay are auctioning off a piece of signed album artwork in aid of Oxfam’s emergency coronavirus appeal.Designed by contemporary artist Pilar Zeta, the collage was originally created for Chris Martin and co.’s seventh studio album ‘A Headful Of Dreams’, which came out back in 2015.The piece will go up for auction at Bonhams Knightsbridge next Tuesday (October 13) and is expected to fetch an estimated £20,000-£30,000.