John Brown ( British Army soldier ) John Henry Owen " Busty " Brown DCM ( died 1964 ) 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 111d 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 Blechammer . 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 the conditions better , he was suspicious of what the Germans were planning . After a carefully orchestrated row with the senior British NCOs at Blechammer he persuaded the Commandant , Rittmeister Prinz Von Hohenlohe , to transfer him back to Stalag 111d . He arrived on 12 June 1943 where he was selected by Major Heimpel of the Gestapo to be senior British NCO of Special Detachment 517 based at Genshagen , in the Teltow - Fläming district of Berlin . Throughout all this time , while being distrusted by the British P . O . W . s , he was reporting to MI6 by coded letters , giving guidance on targets for bomber attacks . More particularly he was engaged in subverting the German proposal to form a British Free Corps to fight for Germany . His cohorts included opera singer Margery Booth , a fellow British spy , who on one occasion whilst entertaining the camp inmates sang before Hitler just after Brown had hidden secret documents in her dress ; Hitler subsequently sent her red roses wrapped in a Swastika flag . Brown was instrumental in identifying the British traitor John Amery , and both Brown and Booth had contact with William Joyce ( Lord Haw - Haw ) , and were recruited by Joyce as a broadcaster on the German Concordia radio service ; both later identified him post war , and were witnesses at his trial . At one point Brown was confronted by Major Heimpel with a statement from a traitor giving details of Brown ' s espionage activities , but Brown blamed it on some of the Jewish inmates , saying they were out to destroy the idea of a British Free Corps . The Germans believed him , but Heimpel still believed that he was a secret agent , and when the British Free Corps were disbanded Himmler ordered Brown ' s arrest . As the Allied forces entered Germany , Brown and a friend managed to kill an SS Colonel , steal his car and make contact with US Army forces . However , once back with British forces he found himself facing a charge of aiding the enemy . Word of his secret work for the Allies soon came from London , and he was awarded the Distinguished Conduct Medal in recognition of his achievements . After the war he was the chief prosecution witness at 20 treason trials . Later life . He wrote of his wartime exploits in a book , " In Durance Vile " ( Hale 1981 ) , concluding " . . . I was only able to do what I did because of my Christian belief which sustained me in my durance vile through not only the danger , but the hopeless dreariness of prisoner - of - war life " . Brown ' s story is recounted from the perspective of Reg Beattie , one of the members of his team , in the book about Reg ' s POW diary entitled " Captive Plans " . After working as a businessman in Newcastle , he moved to Dorset , where he died in 1964 .