Claude Dansey Lieutenant Colonel Sir Claude Edward Marjoribanks Dansey ( 10 September 1876 in South Kensington – 11 June 1947 in Bath , Somerset ) , also known as Colonel Z , Haywood , Uncle Claude , and codenamed Z , was the assistant chief of the Secret Intelligence Service known as ACSS , of the British intelligence agency commonly known as MI6 , and a member of the London Controlling Section . He began his career in intelligence in 1900 , and remained active until his death . Early life . Born in 1876 into a dysfunctional family of nine children , Dansey and his siblings were subjected to military discipline at the hands of their soldier father ( Edward Mashiter Dansey ) , with punishments that included beatings even for minor misbehavior , their mother being an inebriate . They hated each other , as well as their father . Educated at Wellington College , he joined the British Army at the age of 20 , serving in South Africa during the Boer War , because his father would not have allowed him any other vocation . On 13 June 1898 he joined the militia as second lieutenant in the 5th and 6th battalions Lancashire Fusiliers , being promoted to lieutenant on 9 November . On 16 August 1899 he was seconded for service with the British North Borneo Company . His regular Army rank as lieutenant in the Lancashire Fusiliers was dated 15 August 1900 . On 1 March 1902 he was again seconded , as a Staff Lieutenant for Intelligence in South Africa , then on 24 June he was appointed aide - de - camp to the Brigadier - General commanding the Harrismith District , Charles James Blomfield . He was transferred from a supernumerary lieutenancy onto the establishment of his regiment on 17 September 1902 . On 4 November 1904 he was seconded for " special extra - regimental employment " and on 24 October 1906 he resigned his commission . On 10 April 1907 he was promoted to captain on the Reserve of Officers . He was recruited by MI5 and put in charge of " port intelligence " and the surveillance of civilian passengers during World War I . He was inadvertently responsible for allowing Leon Trotsky to return to Russia in 1917 . Later , he joined M05 ( forerunner to MI6 ) . His talents were developed there ; " on at least two occasions , assets he developed within the Irish nationalist movement were able to warn British Intelligence about plans to dynamite Buckingham Palace . " Many of his sources included American industrialists , who would eventually make up much of his extensive contact list . He worked in Switzerland and the Balkans until 1919 . After the war he went into business , but remained a part - time agent . After losing his money in the Wall Street Crash , Dansey worked as a full - time agent for MI6 in Italy to keep tabs on Mussolini ' s Fascist movement , but was unimpressed with the service , which he believed to be incompetent . Z organization . While assigned as chief of station in Rome , Dansey noted several major weaknesses in MI6 : With this in mind , Dansey relied heavily on his American and industrialist contacts , as he felt businessmen knew more about intelligence gathering than the MI6 officers . They focused on the bottom line , ignoring the petty prejudices and favor - seeking that plagued the system at the time , travelled widely on their own dime , had intimate connections with other foreign businessmen and were their own experts . Ultimately , Dansey was convinced what he saw was a disaster waiting to happen , so he set up a parallel MI6 structure , a hidden shadow network that could take over when the inevitable happened . By 1936 , Dansey ' s " Z Organization " ( after his own codename , Z ) had over 200 executives , most doing it for the thrill of espionage . They were not allowed to take extreme risks , write anything down , take pictures or carry spy equipment . Alexander Korda used his company , London Films , as an excuse to visit sensitive areas while " searching for film locations " . These businessmen and journalists used their own credentials as cover . Meanwhile , Dansey was promoted to head the covert intelligence operations desk from its London headquarters . Then World War II broke out and the intelligence disaster Dansey predicted came to fruition . The Hague was the major shipment point for MI6 operations at the time , gathering information from all over Europe and sending them to London . Unfortunately , it was headed by retired military officers Sigismund Payne Best and Major Richard Stevens , who had little intelligence experience . They had been penetrated by a Dutch asset , who was really working for the Nazi ' s SD and revealed the identities of all agents and assets . SD officer Walter Schellenberg posed as a military officer in the German underground , wishing to approach Best and Stevens , who snapped the bait and were captured at Venlo in September 1939 . A few days later , the Nazis knew everything and the entire MI6 structure was destroyed . Activation of the Z organization . Immediately , Dansey switched on his Z Organization , saving MI6 . Within weeks , his Z Organization was providing more and better intelligence than the old structure . " Although the Soviets were unaware , Dansey ' s operation often provided the difference between victory and defeat on the Eastern Front . " All this only won him grudging respect , even though he was promoted as deputy to the new head of the agency , Stewart Menzies . This was because Dansey was spiteful , vindictive , short - tempered , and hated anyone with a university degree . Everyone grew to hate him . As the Nazi defeat became inevitable , Dansey appeared to have outlived his usefulness . In 1944 , they assigned him to a meaningless post without much to do and pressured him to resign . He left without a word of thanks or any pension . Dansey died in June 1947 of heart disease ; a few old friends from the Z Organization attended his funeral . Prior to his death , Dansey had been " bothered by a strange incident . " Someone had painted a huge " Z " on his front door one morning , and even though only a few people knew his codename , he was never able to figure out who it was . " It was " , according to Anthony Read and David Fisher , " one of the few mysteries he could not solve . "