John Hoyland is reckoned by many both here and abroad to be this country's finest abstract painter. A key figure for younger artists and critics, he has been both loved and hated to excess. As a major retrospective of his work opens in London, here is a film that stays close to the artist during six days when he faces hostile criticism, starts a new painting and explains why, in bleaker moments, painting can seem ' like flicking away in a corner with a feather duster '.