After the war, Jones entered the Westminster School of Art, where he developed an interest in Post-Impressionism and studied under the English artist Walter Sickert, among other influential teachers. He also became increasingly attracted by Roman Catholicism, and in 1921 he converted, choosing “Michael” as his confirmation name.
It was probably the priest who received Jones into the Church, who suggested that he contact the Catholic artist Eric Gill. Gill ran the The Guild of St Joseph and St Dominic|Guild of St Joseph and St Dominic, based on the medieval guild model, in Ditchling, Sussex. Jones joined the guild and learned wood and copper engraving as well as experimenting with wood carving. Jones soon began producing book illustrations for the[St. Dominic’s Press, and he would later illustrate for The Golden Cockerel Press, for whom he engraved the Cockerel itself in 1925.
Eric Gill split with the Guild of SS. Joseph and Dominic and moved with his family and some followers to Capel-y-ffin, a village in southern Wales, to pursue a rural way of life. Jones spent much of the years 1924 to 1927 living with the Gills and assorted hangers-on in a rambling former monastery just outside Capel-y-ffin. He had already become engaged to Gill’s middle daughter, Petra, whose characteristic long neck and high forehead continued as standard female features in Jones’s artwork for the rest of his career, even though his engagement to her did not last more than a couple of years. Jones continued to visit his family home in Brockley until the mid 1930s and some of his sketches depict the house and garden.
Jones’s major illustrated series include wood engravings produced for editions of ”The Book of Jonah”, ”The Chester Play Of The Deluge”, ”[[Aesop’s Fables]]” and ”[[Gulliver’s Travels]]” as well as for a Welsh translation of the Book of Ecclesiastes, ”Llyfr y Pregethwr”. He produced an important group of copperplate engravings for an edition of ”[[The Rime of the Ancient Mariner]]”. He also executed commissions for one-off engravings such as his illustration for T.S. Eliot’s ”The Cultivation of Christmas Trees”.
Despite his success and growing reputation as an illustrator, Jones seems to have become disaffected by the medium. He professed great disappointment in the way that his illustrations for ”Gulliver’s Travels” had been subsequently hand-coloured by art students, and complained about the reproduction of the very dark wood engravings for ”The Chester Play of The Deluge”. This may have influenced his decision later in life to concentrate on painting. His style changed over time from more traditional watercolour landscapes to a unique mixture of pencil and watercolour resulting in dense and busy works full of symbolism. His best-known paintings include early seascapes such as “Manawydan’s Glass Door” and later works on legendary subjects, such as ”Trystan ac Esyllt” (Tristan and Iseult). He is also much admired for a genre that he devised later in life, which he termed “painted inscriptions”, and these exert a continuing influence on calligraphers.