sent from Morse equipment on board Royal Navy ships off the Isle of Wight. Kipling is thought of as a quintessentially late-Victorian author, but here he looks to the future, more in the manner of H.G. Wells, as his characters fret over technical matters such as induction and radio frequencies. To the readers of this fictional first instance of radio interception, the process seemed utterly magical. The Morse instrument ‘ticked furiously’, and one of the listening party observes that it reminds him of a séance, with ‘odds and ends of messages coming out of nowhere’. His companion retorts that spiritualists and mediums ‘are all impostors’, whereas these naval messages that they are eavesdropping on are the real thing.2
Kipling’s ‘Wireless’ is the first public discussion of the secret business of signals intelligence, or ‘sigint’. The magical process of extracting information from the ether would be one of the twentieth century’s most closely guarded secrets. Initially, producing ‘sigint’ only required equipment that would allow a third party to eavesdrop on a conversation broadcast by a radio transmitter using ‘wireless telegraphy’, but as this possibility became more widely known, communicators often resorted to using cyphers to keep their messages private. Thereafter, producing sigint usually required skilled listeners to capture the message and then a team of code-breakers to unscramble it. If the message was sent by cable rather than wireless, the listening-in process could be no less difficult than the code-breaking, or ‘decyphering’.
What did Britain’s code-breakers make of Kipling’s public airing of their black arts? The simple answer is that there were none to ask. Indeed, there had been no British code-breakers for more than fifty years. In the distant past, Britain had possessed a ‘black chamber’ in which skilled ‘cryptanalysts’ had broken the codes contained in diplomatic correspondence and private letters. These arcane skills resided in the ‘Secret Department’ of the Post Office. However, in 1847 this was exposed in a scandalous episode when the House of Commons heard that the Home Secretary had ordered the interception of the private correspondence of the heroic Italian nationalist in exile, Giuseppe Mazzini. Shocked Members of Parliament ordered an inquiry, leading to the closure of the ‘Secret Department’, just as the telegraph initiated what we now understand as a Victorian communications revolution. By 1904, Britain had been without a code-breaking centre for more than half a century3
The immediate origins of MI5 and its sister service SIS (often known as MI6) can be traced to scares about German espionage in 1909. But British code-breaking was not revived until the very eve of the First World War. On 2 August 1914 the British Army set up a secret code-breaking section called MIlb. Soon, specialist Army units at various locations in Europe and the Middle East were busy intercepting German radio communications. One of the largest sites was the intercept station in Mesopotamia. In December 1916 the military code-breakers of MIlb were given a fabulous Christmas present when the drunken chief of the German signals organisation in the Middle East sent all his Radio Operators a seasonal greeting using the same obvious formula in no fewer than six different codes. Up until that point the British had only been able to read one of these codes, but with these clues they could read all six. In the First World War, the Second World War and again in the Cold War, poor discipline by the human operators often proved to be the great weakness in otherwise impregnable cypher systems.4
The Royal Navy code-breakers, who had established themselves in the Admiralty’s ‘Room 40’, achieved even greater success. Famously, they broke the ‘Zimmermann Telegram’, a message sent from the German Foreign Minister, Arthur Zimmermann, suggesting an alliance between Germany and Mexico against the United States. As an inducement, Mexico was to be offered the return of her lost territories in Texas, New Mexico and Arizona. These revelations, made public in March 1917, were central in bringing the United States into the First World War on the side of Britain and France. The American entry into the war, together with a tightening blockade, persuaded Germany to seek an armistice the following year. The code-breakers of Room 40 celebrated with champagne. There are few more significant examples of the direct impact of code-breaking upon international relations.5
In 1919 the British government’s Secret Service Committee, chaired by Lord Curzon, the rather formidable Foreign Secretary, recommended that a unified peacetime code-breaking agency should be created. This involved the difficult merger of two quite separate organisations. The head of the Army code-breakers, Major Malcolm Hay, was awkward and argumentative, while his naval equivalent, Commander Alastair Denniston, proved to be suave and diplomatic. Denniston secured the job as chief of a new combined code-breaking organisation, which initially consisted of around two dozen intelligence officers and a similar number of clerical staff, and found himself installed in splendid accommodation at Watergate House in The Strand, next to the Savoy Hotel. Formed on 1 November 1919, the new organisation was given the name ‘Government Code and Cypher School’, or GC&CS, which was not inappropriate, since the leading code-breakers devoted a great deal of time to the patient training of new initiates.6 Both during the First World War and in the interwar period about half the staff of GC&CS and its predecessors were women, mostly in the clerical grades.
Almost immediately, GC&CS adopted a disingenuous description of its duties that would remain in place until the 1980s. Publicly, its functions were described as merely defensive; in other words, it was to assist in the provision and protection of codes and cyphers used by government departments. However, its more secret duty was to give priority to offensive activity, namely attacking the cypher communications used by foreign powers. GC&CS gradually shifted its focus to diplomatic traffic, and at the suggestion of Lord Curzon it was transferred to the control of the Foreign Office. It seemed natural that within the Foreign Office structure it should be placed under the supervision of Britain’s traditional overseas intelligence service, SIS, which recruited human spies. But a subliminal naval influence remained. The talented Chief of SIS, Mansfield Cumming (known within the organisation as ‘C’, the name by which the head of SIS would continue to be called), was a former naval officer. Cumming died in harness in 1923 and was succeeded by another sailor, the former head of Naval Intelligence, Hugh ‘Quex’ Sinclair. Naval intelligence and naval signals officers continued to exercise a profound influence on GC&CS and its successors as late as the 1970s.
The means by which Britain collected its intelligence was changing. During the First World War, much of its intelligence work had involved overhearing military wireless messages by means of receiving stations scattered around Europe, the Mediterranean and the Middle East. The shift to diplomatic traffic meant undertaking more work on encyphered diplomatic telegrams sent by cable. Each country had teams of code clerks who carefully encyphered diplomatic messages before they were sent by telegram using a worldwide network of cables. Although government cable censorship had officially ended in 1918, a private arrangement meant that all the commercial cable companies secretly handed over their traffic to GC&CS for copying. Most of the foreign embassies in London used cable companies to send their encyphered messages, and British dominance of international telecommunications networks meant that many of the world’s messages travelled over British cables at some point. Private companies such as Standard Cable & Wireless Ltd were almost an integral part of the worldwide British sigint system. This secret state-private network remained hidden until it was exposed by the journalist Chapman Pincher in February 1967 in the Daily Mail under the headline ‘Cable Vetting Sensation’.7
In 1925 both SIS and GC&CS were moved into Sinclair’s new secret service headquarters at Broadway Buildings, opposite St James’s Park tube station, which its occupants thought ‘more dingy than sinister’. The walls of the corridors were painted dark brown to a height of about four feet from the floor, and the ancient lifts moved between the many storeys with a slow clatter. The code-breakers were given the third floor. From here, the sigint product, which consisted of the verbatim text (or sometimes summaries) of the messages of foreign governments was distributed around Whitehall in files with special blue jackets that became known as ‘BJs’. GC&CS worked on the cyphers of many