Gregory spent 20 years serving in the British Army, retiring in 1998 as a Major in the Grenadier Guards. During his military career, he served in more than 10 countries. His last several years in uniform were spent in the UK Ministry of Defence with responsibility for a range of specialist equipment requirements and technical research programs, including in relation to the development of military airships. In this role, he also set up and managed the aerial surveillance for the 1996 Atlanta Olympics, using a commercial airship. After leaving the British Army, he has been involved in the design, development, production, crew training and operation of both airships and aerostats in several countries for different companies and governments, including in the USA, the Caribbean, Europe and the Middle East. He has also acted as a Subject Matter Expert on airships for The Boeing Company.
Since 2005 he has managed airship and aerostat programs, initially for the UAE Government and subsequently for the Saudi Government. He founded Airships Arabia in 2014. In addition to being a long-serving Council Member of The Airship Association, the London-based global body for the promotion of airships, and former Editor of its quarterly journal, AIRSHIP, he is a Member and former Chair of the American Institute of Aeronautics and Astronautics Lighter-Than-Air Systems Technical Committee. His hobbies include flying and skydiving.