I am sure you can understand why he so frightens the FCO. The normal threats an employer can make against an employee — the loss of home, salary, position and, in Pasquill's case, liberty — could not intimidate him. He was a man with the inner freedom the Stoics so valued. He had trained himself to be indifferent to the threats and blandishments of official society. Even though governments around the world read his revelations with varying degrees of horror, the FCO dropped the prosecution. Legally, its case was watertight. Pasquill had admitted leaking official secrets with pride. But Whitehall knew all too well that he would use the dock as a platform to appeal to the jury and the wider public.

Now Pasquill is bringing what to my unqualified eyes looks like a hopeless claim of unfair dismissal. On the face of it, a civil servant who passed a filing cabinet full of official secrets to the press cannot seriously claim that the state exceeded its powers by firing him. Yet if you look at his revelations, his claim makes more sense. 

As his affidavit to the employment tribunal dryly remarks, "The documents that I disclosed showed that the FCO and other UK government departments were continuing to work with and assist organisations that promote extreme Islamist politics. My concern was that this policy would have the effect of legitimising and supporting groups with extreme Islamist politics and that such an effect was entirely contradictory to FCO and UK government policy of attempting to prevent the radicalisation of young British Muslims. Furthermore, I believe that the FCO and other government departments pursue a policy of portraying these organisations as mainstream and moderate."

Who is the traitor and who the patriot in these circumstances: the dissident civil servant or the two-faced government? Who, to be blunt, is more deserving of summary dismissal?

Journalists covet whistleblowers for the mercenary reason that they fill our pages and make our names. Only after we have wrung them dry do we want to know why they risked their careers to reveal their employers' crimes and follies. I thought that Pasquill could supply a lucid answer. He is an ascetic intellectual: a thin, quiet man, who thinks carefully before speaking and upholds the English intelligentsia's customary disdain for smart clothes and dental hygiene. Yet my attempts to prod him into giving me a pat explanation got nowhere. He had studied the Holocaust, he told me, and learned the importance of documenting state crimes from Raul Hilberg's The Destruction of the European Jews. The scene in Claude Lanzmann's film Shoah, when Hilberg holds up a timetable listing the trains that took Jews to extermination camps, stayed with him and taught him that you must get official papers on the public record at any cost. Yet when I asked him if it was the transfer of Tsarist and Nazi anti-Semitism from Europe to the clerical fascists of the Muslim world that moved him to take on the FCO, he looked blank. The thought never occurred to him. 

He is too much of an intellectual to allow me to think that a neat, coherent motive explains his actions. Instead, he says without elaboration that he found the behaviour of Jack Straw and the wider liberal establishment he had served so loyally "shocking".