A further important factor working to Cumming's benefit was the restricted view he took of what the Secret Service Bureau should actually do. There is no suggestion in the surviving documentation that he ever saw the function of his organisation as being more than the collection and distribution of information, as requested by other government departments. At no stage did he seek to offer policy advice, or even very much to analyse or manipulate the information gathered by his officers and agents. For him, the Bureau was simply an expert organisation, designed to respond as best it could to the requirements of customer departments. And, unlike some others in the intelligence world - Colonel French during the war, Basil Thomson immediately after, and even Cumming's successor, Hugh Sinclair, in the inter war years - he never showed any tendency towards empire-building. When the Bureau grew, it did so organically and in response to customer demand. Cumming's institutional ambition was not in the slightest acquisitive (which could have made him enemies), but consistently protective, vigorously defending his organisation from the threatened depredations of other departments. His obsession, moreover, with secrecy (the "first, last and most necessary essential") had a beneficial and self-effacing effect. By consistently maintaining as low a profile as possible, neither he nor his organisation appeared to threaten anyone else.

A final, and extremely significant, feature of Cumming's time as Chief is the shrewd political judgment he demonstrated in the face of the 1919 War Office proposal to amalgamate his department and MI5, at a time when ministers and officials alike were gripped by fears that Red Revolution might engulf the United Kingdom. Everything in Cumming's class and career background would have disposed him towards diehard right-wing political attitudes, militantly opposed to the threat of the Labour movement and socialism (let alone that of Communism). But what is remarkable about Cumming, in contrast to other toilers in the intelligence vineyard, such as Blinker Hall (a Conservative MP from 1918 to 1923), Thomson and Sinclair (certainly when he was Director of Naval Intelligence), who were prepared at times to let their right-wing political views supersede the obligations of constitutional government, is that, whatever his private political opinions, he carefully and wisely distanced himself and his organisation from domestic British politics. He saw clearly, as his successor Stewart Menzies was also to do twenty-five years later, the absolute necessity of keeping domestic and foreign intelligence work separate. Anticipating the possibility of a Labour government, and managing to do so in an admirably unhysterical way, Cumming asserted that combining his organisation with M15 and getting involved in secret service against domestic political targets could jeopardise the effectiveness of foreign intelligence work by prompting public and parliamentary attacks on the intelligence machine as a whole. As with his passion for motor cars, speedboats and aeroplanes, Cumming, a nineteenth-century Victorian with a lively twentieth-century interest in technological advances, may have been more prepared to accept political change than many of his contemporaries. Or he may simply have appreciated that the active espousal of anti-left-wing politics could damage the work of his beloved Bureau. Whatever the reason, his decision to distance the Bureau from domestic security and intelligence work was absolutely sound.

Cannot do any work in office. Been here five weeks, not yet signed my name. Absolutely cut off from everyone while there, as cannot give my address or be telephoned to under my own name. Have been consistently left out of it since I started. Kell has done more in one day than I have in the whole time...

The system has been organised by the Military, who have just had control of our destinies long enough to take away all the work I could do, hand over by far the most difficult part of the work (for which their own man is obviously better suited) and take away all the facilities for doing it.

I am firmly convinced that Kell will oust me altogether before long. He will have quantities of work to show, while I shall have nothing. It will transpire that I am not a linguist, and he will then be given the whole job with a subordinate, while I am retired - more or less discredited.

Called on Kell at his request handed over my small safe and the keys to my desk to his Clerk... He asked me if I should object to his coming next door, but t told him that I thought it would interfere with my privacy in my own flat and I begged he would not go forward with any such scheme. I would rather he were not in this immediate neighbourhood at all.

Cumming's most remarkable, though not his most reliable, agent was Sidney Reilly in St Petersburg, the dominating figure in the mythology of modern British espionage. Reilly, it has been claimed, "wielded more power, authority and influence than any other spy", was an expert assassin "by poisoning, stabbing, shooting and throttling", and possessed "eleven passports and a wife to go with each". The reality, though far less sensational, is still remarkable. Reilly was born Sigmund Georgievich Rosenblum in 1874, the only son of a rich Jewish landowner and contractor in Russian Poland. Some time in the 1890s he left home, broke off all contact with his family, and emigrated to London. At the turn of the century, having changed his name to Reilly, he moved to Port Arthur, the base of the Russian Far Eastern Fleet, where he worked first as partner in a firm of timber merchants, then as manager of the Danish Compagnie Est-Asiatique. By the time Reilly returned to London on the eve of the Russo-Japanese War in 1904, he had become a self-confident international adventurer, fluent in several languages, already weaving around his cosmopolitan career a web of fantasy which has since ensnared most of those who write about him. "He had", writes his most recent biographer, "passed his test with the SIS with flying colours, and they decided that they had a most promising recruit on their hands, who merited very special training". Not the least problem with this romantic view of Reilly's intelligence initiation is that SIS did not yet exist. It is quite possible, though there is no proof, that Reilly did provide NID with intelligence on the Russian Far Eastern Fleet during his years in Port Arthur. But it is scarcely possible that his unusual experience of higher education over the next few years was specially devised as a training programme by NID. In 1904-5 he successfully completed a year's course in electrical engineering in the Royal School of Mines. In October 1905 he went up to Trinity College, Cambridge, as an "advanced student" but left two or three years later without taking any degree.