Self-taught artist and poet with a mystical outlook, born in Colombo, Ceylon. Began to draw and paint aged 29 after joining the Colombo Port Commission as a draughtsman, continuing in that occupation until retirement. He moved into pure abstraction about 1947. Claessen was a founder-member of the ’43 Group in Ceylon, also belonging to Victorian Artists’ Society in Melbourne and in London Free Painters and Sculptors, Hampstead Artists’ Council and Islington Art Circle. Showed at Venice Biennale in 1956 and at its equivalent in Sa˜o Paulo, Brazil, in 1959, where he won an award. Solo shows included Velasquez Gallery, Melbourne, 1947; Archer Gallery, 1949; and New Vision Centre, 1962. In 1945 War Artists’ Advisory Committee bought a work by Claessen, who sometimes signed with initials only.