Around 33 million people may have accessed U2’s Songs Of Innocence album since it was made available for free to 500 million iTunes users last week, but the campaign has resulted in sales of only 6,047 additional copies from the band's 19-album catalogue - with less than 60 of those sold in High Street shops.

That's according to analysis of Official Charts Company data by the Entertainment Retailers' Association.

ERA chairman Paul Quirk said that the figure "vindicates our view ...