London - Booker Prize winner Margaret Atwood's The Blind Assassin was last night beaten to the UK's richest fiction award by Australian writer Kate Grenville. The £30,000 Orange Prize, open to women writers, went to Grenville for her novel The Idea of Perfection. The Orange Prize is for excellence, originality and accessibility in women's writing. It honours the best novel written by a woman and published in the UK.