Daughter of the former emir of Qatar and sister of the current, titled Her Excellency Sheikha Al-Mayassa bint Hamad bin Khalifa Al-Thani, has been named the most powerful person in the art world. At 30-years-old she has control over buying art for her royal family. On average, more than £600m are spent a year on art acquisitions, including works by Paul Cezanne, Warhol, Lichtenstein, Bacon, Hirst, Picasso and Rothko.