Schooled at Charterhouse, and a graduate of the Royal Military Academy at Sandhurst, Robertson spent only two years with the Seaforth Highlanders before resigning his commission, followed by spells in the City and police work in Birmingham. In 1933 he transferred to the Security Service, still aged only twenty-four, and in no time at all established an enviable reputation as a counter-intelligence officer par excellence. All that was required were a few rounds of drinks in a Mayfair saloon bar. Aside from Nazis, Blackshirts and the Irish Republican Army, during the last year of peace the long list of subversive organisations monitored by MI5 included the Communist Party of Great Britain, lately implicated in a spy ring at the huge Woolwich Arsenal. With the ‘red menace’ regarded as a clear and present danger, companionable Captain Tommy duped a suspect Foreign Office cipher clerk named John King over drinks at the Bunch of Grapes on Curzon Street. After King passed out drunk Robertson borrowed his keys, burglarised his office and recovered a batch of incriminating papers meant for dispatch to Moscow.
