Works by the painter, owned by the controversial "playboy" socialite, were offered at Christie's New York this month

Plus, Joan Mitchell and Claude Monet at the Fondation Louis Vuitton and England's Tudors head to New York

Georgina Adam and Mark Hollingsworth investigate a troubling case of serial reattributions, showing how easily scholarly “opinion” translates into financial fact

The former husband of heiress Petra Ecclestone denies any criminality and says he will contest all charges