A Guernseyman, John Symons was educated at the Royal Military Academy Sandhurst. He spent 33 years in the British Army as a Regular and Territorial officer serving in both the cavalry and the infantry. He fought in the Dhofar War and commanded sub units in Northern Ireland (South Armagh and Belfast) in the 1970s. Staff appointments during his service included tours with HQ 1 (British) Corps in Germany and the Ministry of Defence (Army Staff Duties) in London. He was also a member of the directing staff of the Army Staff College. As a business school academic, he published extensively on the topics of leadership, management learning and development. In 2006 he established the Cancer of Unknown Primary (CUP) Foundation – an international charity working to raise awareness, promote research, and support those affected by CUP.