General Gwyn commissioned into the Royal Marines in 1990. His time as a junior officer was spent in the Commando Logistics Regiment, competing for the Royal Navy and Royal Marines in cross-country skiing and on operations in Northern Ireland with 42 Commando RM.

A graduate of the Advanced Command and Staff Course at the Military College Shrivenham, where he completed a master’s degree in Defence Studies in 2004, he went on to serve as a Lieutenant Colonel overseeing global operations in PJHQ, before a Commanding Officer appointment in 2009. On completion of his command tour he was promoted to Colonel and deployed for 12 months to Afghanistan, for which he was awarded an OBE, returning to the UK in 2012 as the Military Assistant to the Prime Minister in No 10 Downing Street.

After two years in No. 10, he completed the Higher Command and Staff Course, was promoted to Brigadier and took up a 3* civilian appointment in the Cabinet Office as Deputy National Security Advisor for Conflict, Stability and Defence. In April 2017 he moved back to the military and took command of 3 Commando Brigade, conducting exercises and overseeing operational deployments around the world. He was promoted to Major General in January 2019, in which rank he served first in the Royal Navy as the Assistant Chief of Naval Staff and subsequently commanded a tri-service organisation.

In August 2022 he was appointed Vice Chief of the Defence Staff and promoted to General. Since August 2024, General Gwyn has been the Strategic Advisor to the Secretary of State for Defence. In this role, he has negotiated the UK’s Defence Agreement with Germany and is cohering the UK’s strategic partnership with Norway. He lives with his wife and children and enjoys a range of activities including sailing, skiing and creative writing.

First Sea Lord and Chief of Naval Staff
The First Sea Lord is the professional head of the Royal Navy and a member of the Defence Council. He is responsible to the Secretary of State and the Chief of Defence Staff for the fighting effectiveness, efficiency and morale of the Naval Service.

As a member of the Defence Council, the First Sea Lord supports the Secretary of State in the management and direction of the Armed Forces through prerogative and statutory powers. As a member of the Chiefs of Staff Committee, he advises CDS on maritime strategy and policy. He has a collective responsibility for providing strategic direction to the department, managing performance and ensuring that the Royal Navy delivers the required outputs.