John was educated at Wadham College, Oxford. From university, he joined Beecham Group Limited (now part of Glaxosmithkline plc) where he held a number of increasingly senior commercial and financial management roles at home and overseas and qualified as an accountant.
Subsequently he was manager of accounting, Middle East and Europe, for a division of International Harvester Inc. (now Navistar Inc.), financial controller and then managing director of the UK subsidiary of Delalande SA (now part of The Sanofi-Aventis Group) and financial director of part of Hays Plc, at that time involved in transport and warehousing. His industrial career thus encompassed pharmaceuticals, engineering and logistics.
In 1993 he joined a small number of colleagues to establish a new financial services group and founded Cavendish Administration Limited, the administrative arm of the business. Cavendish was acquired by the PraxisIFM Group in November 2015. He is also a non-executive director of Advance Umbrella Fund plc, an investment company listed in Dublin.