Jonathan was born in that most English of towns, Leamington Spa, but, as he was once told in the The Pendre Inn in Cilgerran, near Cardigan, is "of the blood". His mother's family were from that area and his father's from Bonamaen in the Swansea Valley. Both his parents were Welsh speakers, but Jonathan's Welsh sadly lapsed at the age of four.

He attended King's School, Worcester where he spent a good deal of time rowing on the River Severn. He was also Rugby Secretary, which hopefully, in spite of the many intervening years, has left him with some of the skills necessary to discharge the duties of Secretary of Wales in London. He read Law at Trinity Hall, Cambridge, before training as a solicitor at Allen & Overy. On qualification, he chose the path of litigation and dispute resolution. 27 years later, after a number of years as a partner at Taylor Wessing, he is a full time consultant at Goodman Derrick LLP, where his practice covers a wide range of civil and commercial disputes, including fraud, banking and finance, commercial contracts, claimant professional negligence, cross-border disputes, media and publishing, IP and IT and trust and probate claims. He is qualified as a Fellow of the Chartered Institute of Arbitrators and is active in the field of mediation on behalf of clients.

Jonathan lives in Richmond, conveniently just around the corner from the London Welsh Rugby ground, where he is a member and supporter. He and his family regularly travel to South and West Wales, where Three Cliffs Bay, Rhossili, Mynt and the Preseli mountains are amongst their favourite places.