Born in London, Wells was brought up in an artistic community in Ditchling, Sussex,and  educated at Epsom College before going to University College Hospital, London, in 1925 to read Medicine. However, as Cross makes clear, he had known Cornwall all his life, his mother being Cornish and coming from St Mary near Padstow. For many years his childhood summers were spent in North Cornwall. In 1927 he began to attend evening classes at St. Martin's School of Art, and on a visit to Cornwall during his summer holidays the following year spent a month studying at Stanhope FORBES' School; during this period he was also introduced to Ben NICHOLSON and Christopher WOOD. 

 He qualified as a doctor in 1930 and worked in hospitals for six years before moving to St. Mary's, Isles of Scilly where he worked as a GP (1936-45). In 1945 he moved to Newlyn where he took over Stanhope FORBES' Anchor Studio, working there and in the former Infants School (Trewarveneth Studio) which he shared with sculptor Denis MITCHELL, both of which working studios he bequeathed in trust for the future benefit of artists in the area.

 As an abstract and modernist painter, he was more attracted to St Ives, and was a founder member of the CRYPT GROUP and the PENWITH SOCIETY.  He also worked briefly as an assistant to Barbara HEPWORTH (1950-51).  Since his death in 2000 the Borlase SMART-John WELLS Trust has been formed, headed by the Tate Gallery Director, Sir Nicholas Serota, to create a permanent artistic and educational centre in Wells' studios for the use of artists locally. His portrait was painted by fellow artist Ken SYMONDS (See Hardie, section B in the Newlyn Diary).