For the past six decades, John Loker has produced rigorously conceived and visually mesmerising works of art across media. Known as a photographer, sculptor, assemblage-collagist and above all painter, he is one of modern Britain's most original and category-defying artists. Lewis traces Loker's unusual artistic journey from Bradford College alongside fellow students David Hockney, Peter Kaye, David Oxtoby, Norman Stevens and Michael Vaughn, his education at the Royal College of Art, rise to international attention in the 1970s and recent focus on space and the horizon of our planet.Horizons, Zones and Outer Spaces is published by Elephant in association with Flowers Gallery.