Owen Fitzgerald Marsh

Owen Fitzgerald Marsh spent more than two decades in defence analysis, latterly as a senior researcher at the Royal United Services Institute in London and, before that, at the Stockholm International Peace Research Institute, where he built comparative datasets on procurement and force structure. He became an external advisor to the Institute in 2021.

He reviews the methodology behind studies that compare defence budgets and strategic posture across allied states, with a particular eye on the pitfalls of open-source defence indicators — reporting lags, currency effects, and the off-budget spending that distorts headline figures.

Owen meets the security programme quarterly to assess draft findings and advise on data-sourcing standards. He gives background briefings to researchers and officials but does not take on-the-record media interviews.