A Welsh artist, Janes was born in Swansea where he attended Swansea School of Art and Crafts. Something of a prodigy, he exhibited at the 1928 National Eisteddfod at 16 and three years later was commissioned  to paint a portrait of the mayor of Swansea. At 20 he won a scholarship to the Royal Academy Schools where he was taught by Thomas Monnington. He shared a flat for a time with fellow student William Scott. In 1932 he became part of the bohemian Swansea group ‘The Kardomah Gang’ that included the poets Dylan Thomas and Vernon Watkins and the Composer Daniel Jones. Janes had a close association with Thomas, sharing flats in and around Earls Court, during which time he painted several portraits of the poet. Three portraits are now in Welsh public collections including the well known oil in the National Museum in Cardiff. He taught in Swansea for many years, broken only by war service in Egypt with the Pioneer Corps. In 1963 he moved to London, accepting a post at Croydon College of Art, and from then until his death he lived at Dulwich. Among the younger generation whom he encouraged were Bridget Riley and Bruce McLean. In 1999 the Glynn Vivian Art Gallery, Swansea, held a retrospective exhibition of his work.