He served in the Royal Army Medical Corps, 224 Parachute Field Ambulance, within the 6th Airborne Division, taking part in the Ardennes campaign and the airdrop over the Rhine at Wesel in March 1945.

[6] Following demobilisation in 1947, Jones's career began in a shared practice with the artist John Petts at the Caseg Press in Llanystumdwy,[7] North Wales, followed soon after by a short, intensive stay at the workshop of the late Eric Gill, where he learned the techniques of lettering and carving in stone.

He painted in watercolour, a medium in which he produced a distinctive body of work based on vernacular calligraphy, a technique in which the artist and poet David Jones was a major influence.

[1] In 1982 he spent a year at Gregynog Hall, working with Eric Gee and David Vickers on the book, Lament for Llewelyn the Last, for which he designed the title page.

[1] Jonah Jones's major public commissions include work for the chapels of Ratcliffe College, Leicestershire; Ampleforth College, North Yorkshire; and Loyola Hall, Rainhill, Merseyside (now moved elsewhere); St Patrick's Church, Newport; the National Museum of Wales, Cardiff; Coleg Harlech, Gwynedd (now in storage awaiting relocation); and Mold Crown Court, Flintshire.

His private work is marked by a preoccupation with Christian imagery and biblical themes (particularly that of Jacob), the Welsh mythological tales of the Mabinogion, the landscape of North Wales, and the Word.