John Henry Owen Brown DCM (c. October 1908 – 15 September 1965) was a Quartermaster Sergeant in the Royal Artillery in the British Army, who served in France at the beginning of the Second World War. He was one of Britain's most successful espionage agents as a prisoner of war following his capture by German forces, and, following the war's conclusion, acted as a prosecution witness in trials for treason. Prisoner of war Before he left England he had been sent on a special course for spies operating in enemy hands. He was told that he would be of more use as a POW than as a combat soldier. He was captured at Dunkirk on 29 May 1940 and remained a prisoner of war until 1945. He volunteered to serve at the Blechhammer POW camp in Upper Silesia, and the fact that he had been a member of the British Union of Fascists before the war helped him ingratiate himself with the Germans and strike up a relationship with the camp commandant. In the summer of 1942 a special camp was established to separate potential collaborators from other British POWs, Stalag III-D near Berlin. This in turn was divided into Special Detachment 999 (an officers' camp) and Special Detachment 517 (for other ranks). Both were presented by the Germans as "holiday camps" away from the poor rations, hard work and cold of normal camps, but the camp security was run by the Abwehr. Brown was one of the prisoners sent to Freigegeben (Open Prison) Stalag III-D for an initial examination. A former member of the British Union of Fascists, he had developed a good relationship with the Germans, which he exploited to run a very efficient blackmarket operation among the conscripted foreign workers, using some of the profits to buy "luxury" items such as extra food, medicine for the camp hospital and even musical instruments for the camp band. Brown also had a hidden radio so was aware of the course of the war. At Stalag III-D Brown quickly realised something was wrong, and after his visit he returned to Blechhammer. There he had met Captain Julius Green, a Jewish-Glaswegian officer who was the camp's dentist. Green gave Brown the codes and the means to pass intelligence back to London through MI9's Escape and Evasion Network. Brown decided to return to Stalag III-D as soon as possible; not only were