Llewellyn began his career in the oil industry in 1980, working both as a journalist and as oil broker in London and New York, with Petroleum Argus, Eperon Petroleum, Albion Oil, Petroleum Intelligence Weekly and OPEC Listener, before joining MRC Business Information Group in Oxford – which later became Lloyd’s List Intelligence after MRC’s acquisition by Informa – where be rose to Managing Director before leaving in May 2003 to establish Petrospot Limited.

Petrospot is a dynamic independent publishing, training and events organisation focused on the maritime and energy transition sectors. Its global publications include Bunkerspot magazine and online information service, the ship.energy intelligence service and a growing library of books on shipping and bunkering. Petrospot also organises globally-recognised training courses such as the Oxford Bunker Course and Bunker Experience and runs major international conferences, including Maritime Week Americas, ARACON, Maritime Week Gibraltar, Maritime Week Africa, Portugal Shipping Week, Middle East Bunkering Convention and the Marine Energy Transition Forum.

Llewellyn is co-creator, founder and owner of London International Shipping Week.