One of the more satisfactory aspects of being a journalist is the discovery that the powerful are hyper-sensitive to any revelation about their activities. The degree of venom and hysteria expressed by the US government in attacking Julian Assange and WikiLeaks reflects this acute sense of vulnerability.
My father, Claud Cockburn, discovered this in 1933 when he left The Times and set up a radical newsletter called The Week, which was a sort of early precursor of Private Eye. His calculation was that there was plenty of information freely circulating in political and diplomatic circles that was hidden from the general public.
He hoped that his small publication would provoke some official reaction, and this he turned out to have underestimated. Since he had started The Week with £40 invested by a friend he had no money for promotion. He had used an old mailing list of 1,200 names, many of who turned out to be dead or otherwise uninterested. After the first few issues, he found that "the number of paying customers secured was seven".
Just as he was suspecting that his big idea was coming permanently unstuck, he was saved by the Prime Minister, Ramsay MacDonald, who was holding an international economics conference in the Geological Museum in London in a doomed effort to grapple with the Depression. A copy of The Week saying the conference was dead on its feet had somehow reached MacDonald, who promptly called a special press conference to warn against the hitherto obscure newsletter as a false and misleading prophet of disaster. Within minutes of MacDonald's denunciation my father was flooded by calls from would-be subscribers.
In 2003 I became interested in how far the authorities had monitored my father's activities, and I wrote to the director of MI5 asking for his files to be declassified. A year or so later, presumably because of my request, 26 bulky folders containing thousands of pages of reports by MI5 officers, policemen and informers about Claud were placed in the National Archives in Kew.
He was first mentioned in a military intelligence document from 1924, when he and Graham Greene, as 20-year-old students, went on a visit to the Occupied Rhineland without getting visas. "Both [men] appear to be authors," an intelligence officer recorded suspiciously.
But the real interest of MI5 in Claud only came when he started The Week. Every detail of its financing, circulation and staff was recorded. Memos spluttering with rage criss-crossed within the Civil Service demanding stern action against Claud for criticising civil servants by name or publishing classified information.
The official security apparatus mobilised to monitor him was impressive. His mail was intercepted, phone calls transcribed, friends interviewed and Special Branch watched his movements assiduously. On one day, 30 March 1940, for instance, a Special Branch officer who called himself "the Watcher" sent in a report about how he had tirelessly followed my father and mother around Tring, Hertfordshire, recording the name of every pub they drank in and the precise times they entered and left.
The purpose of all this was presumably to find the identity of my father's contacts who were giving him classified information. Despite close monitoring, MI5 never took on board that much of what he published came from other journalists who could not get stories into their own publications.
Did all this information give MI5 a clear picture of my father? This entirely depended on the quality of the person who interpreted the reports. Like much intelligence information, there was too much of it and it was of varying quality. For instance, MI5 had good information from the Times correspondent in Berlin who had originally hired Claud. But elsewhere in the file a self-appointed inquiry agent claims there was a "Cockburn machine" in charge of Communist sabotage in Western Europe in the event of war or revolution. Over the years good and bad information about him got blended together.
This habit of obsessive but useless official secrecy affected my father long after The Week was defunct. In 1963 Claud was guest editor of Private Eye and revealed that "C", the head of MI6, was Sir Dick White. Cabinet papers show that Sir Burke Trend, the Cabinet Secretary, summoned a meeting to consider prosecuting my father, but regretfully abandoned the idea on realising that the identity of "C" had long been widely known in Fleet Street.
Discussing the whole issue of secrecy and the media with fellow Whitehall mandarins, Trend came out with a splendid piece of justificatory obfuscation, writing: "It is a matter not so much of concealing as of withholding and what is withheld is not so much the truth as the facts."
As with WikiLeaks, much of the official criticism of my father's publication of classified information in the 1930s was irrational. At one and the same time, angry officials wrote that he was reliant on gossip and his stories were inaccurate, but also that no effort was to be spared in discovering his sources. Opponents of Mr Assange produce similarly contradictory arguments, downplaying the importance of what he has revealed but simultaneously demanding his arrest for high crimes.
There is something more at work here than political establishments trying to protect their access to information as an instrument of authority. The true origin of their rage seems to be the way in which the publication of classified papers, whether they expose real secrets or not, undermines the ability of political elites to present themselves as the all-powerful guardians of secret knowledge essential to their country's well-being.
I am sorry my father died in 1981, long before his MI5 files were released. He had always held that the saying that God was on the side of the big battalions was propaganda put out by big battalion commanders to demoralise their opponents. He would have been delighted that his guerrilla-publication had provoked such rage within the government and so much effort uselessly expended by the security services.
He might also have considered that today there is a certain justice in the US government inadvertently providing so much information to the world at a time when international media coverage of much of the globe is ebbing. Press, radio and TV have all been punished financially by competition from the internet, robbing them of the resources for foreign reporting. Suddenly WikiLeaks exposes a myriad of stories from Argentina to Kyrgyzstan to Korea which the media would have liked to write about.
WikiLeaks' publication of diplomatic cables and frontline military reports does not disclose many real secrets, but this should not obscure the vast importance of its revelations. It discloses to everybody, as my father had sought to do in the 1930s, facts and opinions that were previously only known to a few. Over the last six months its revelations have painted a unique picture of the world from the American point of view at a moment when US political, economic and military leadership is under stress as never before.
The embarrassment of the US government is not that it has lost any real secrets but that it can no longer pretend that it does not know about the often criminal actions of its own forces, or the unsavoury actions of its allies.