As an MI6 field officer, Matthew Dunn recruited and ran agents, coordinated and participated in special operations, and acted in deep-cover roles throughout the world. He operated in environments where, if captured, he would have been executed. Dunn was trained in all aspects of intelligence collection, deep-cover deployments, small arms, explosives, military unarmed combat, surveillance, and infiltration.

Medals are never awarded to modern MI6 officers, but Dunn was the recipient of a rare personal commendation from the secretary of state for work he did on one mission, which was deemed so significant that it directly influenced the success of a major international incident.

During his time in MI6, Dunn conducted approximately seventy missions. All of them were successful. He currently lives in England, where he is at work on the fifth Spycatcher novel.