Etcher and relief printmaker, and teacher, born in Keokuk, Iowa, America. He studied at Ruskin School of Drawing, 1968–71, then became a freelance printmaker. From 1972–89 was a part-time tutor. Showed with RE and RWA both of which he was a member, Oxford Gallery, RA and with Wenniger Graphics in Boston. The Museum of Modern Art, Oxford, included Winkelman’s atmospheric A Light Blanket of Snow in a group show in 2004. Ashmolean Museum in Oxford, National Museum of Wales in Cardiff, Victoria Art Gallery in Bath and Usher Gallery, Lincoln, hold examples. Lived in Headington, Oxford.