John was educated at Trinity College, Dublin. He joined Collett, Dickenson, Pearce in 1972 and over the next 17 years helped to build the company into the largest private advertising group in the country and one of the most famous creative agencies in the world. In 1990 John left CDP as Chairman and Chief Executive and became Chairman of Lazer, the sales and marketing arm of ITV and Chairman of Playback, the management training company he started with Mel Smith and Griff Rhys Jones.

In 1992 John became the founding Chief Executive of Classic FM. In 1996 John was appointed by the Secretary of State to the Arts Council, he also became an operating partner of Electra Investment. In 2006 John became Chairman of Scholtz and Friends, the largest privately owned advertising and marketing group in Germany. He is also an investor in a wide range of companies.