After graduating from St Andrews University (MA Honours), John spent 14 years working for Ford Motor Company. His career with Ford included a two year assignment in Detroit and serving as Director of Finance for the Ford Motor Credit Company.

In 1982 he moved to Wiltshire to join PHH Europe where he became Chief Executive of this £2 billion turnover vehicle management services company. In this role he helped steer the ultimate sale of the company's European operations to BNP Paribas in 2002.

John moved to Bath in 1998 and in 2003 took early retirement to serve in various roles in the private, public and voluntary sectors.

In the private sector, John was the recent Chair of Premier Watercoolers Ltd, and he is currently Chair of JBP Public Relations Ltd, RealTime Risk Assessment Ltd and his son, Jamie Cullum's music business. He is also a Board Member of Internet Eyes Ltd and is past Chair of the CBI South West Region.

In the public sector, he has chaired the New Swindon (Urban Regeneration) Company and the Wiltshire & Swindon Economic Partnership Forum.

In the voluntary sector, John is Chairman of the Royal United Hospital Bath's "Forever Friends Appeal" and a committee member of Quartet Community Foundation.

John also served as The High Sheriff of Somerset for 2011-2012, the Queen's representative for the Judiciary and the maintenance of law and order in the county of Somerset.