I was called up by the War Office to see Captain Archibald Wavell who was then in charge of intelligence, although he was only a captain. He was looking for an officer to send to Russia and thought I might suit the job. I had met Wavell first in Russia when he was learning the language. He sent me to see C (Mansfield Cumming). I went over to his office, which was at that time in Whitehall Mansions, apparently he occupied the top flat, and personally he occupied the turret. I had to climb up very steep stairs to reach his room and he had apparently to lift a brick before you could open the door. I met C, who telephoned for his secretary to take notes. She popped up through a trap door in the floor and was present for the interview. C sent me to meet the Russian Military Attache, Lieutenant-General Nikolai Ermelov, who occupied a flat in the same building. The only remark C made to me was that I might not fit the job as I had not any decorations, however at a second interview with Ermelov apparently my knowledge of Russian made him agree to my appointment. C's suggestion was that I should obtain some fake decorations from Clarksons, which however I did not do.

Dear Scale, No response has thus far been received from London in respect of your oilfields proposal...

Although matters have not proceeded entirely to plan, our objective has clearly been achieved. Reaction to the demise of "Dark Forces" (a codename for Rasputin) has been well received by all, although a few awkward questions have already been asked about wider involvement. Rayner is attending to loose ends and will no doubt brief you on your return.

Questions have also been raised about why Alley should write such a letter and how it would reach Scale. The days of mobile phones were many decades away, of course, and communication was generally either by telegram or letter so a letter is a reasonable way to communicate, sent either by courier or by normal military despatches.

In the absence of evidence to the contrary the letter has to be accepted as genuine or else - and the spectre of this concerns me created ex post facto for the purpose of financial gain, a view which I do not accept and in the absence of proof reject. I have seen criticism of the content of the letter that suggests it does not conclusively show British involvement, the logic of which eludes me. Let me dissect it.

"Dear Scale, No response has thus far been received from London in respect of your oilfields proposal.' There is clear evidence to show Scale's involvement in the destruction of the Romanian oil fields in face of the advancing German troops.

"Although matters have not proceeded entirely to plan, our objective has clearly been achieved." Well, we know things had not gone to plan: the body had been recovered from the Nevka when the intention was that it would never he seen again; Yusupov had been detained at the station on the way to the Crimea, the police had attended the Yusupov Palace as a result of hearing "shots". But if the objective was, as I suggest, to prevent a separate peace with Germany by removing Rasputin, then yes, it had been achieved.

"Reaction to the demise of Dark Forces has been well received by all, although a few awkward questions have already been asked about wider involvement." We know that Purishkevich referred to Rasputin as Dark Forces, and we know from the Scale papers and from his daughter's evidence that her father used the same term when referring to Rasputin - this was the accepted code word for him. This issue is not in doubt and William Le Queux used the term Dark Forces to describe Rasputin as early as 1918. Brian Moynahan provides more information about how commonly the term was applied to Rasputin when he tells us:

On December 8 the Union of Towns, an important municipal body, went into secret session. It passed a resolution: "The government, now become an instrument of the dark forces, is driving Russia to her ruin and is shattering the imperial throne. In this grave hour the country requires a government worthy of a great people. There is not a clay to lose!' Secrets were no longer kept. The resolution was circulated in Roneo script in thousands of copies. Dark forces was simple code for Grigorii Rasputin and those about him.

And I hope no one would doubt he died and therefore it was his "demise". We know that awkward questions had been asked: the Tsar confronted the British ambassador and accused Rayner (although not by name) of being involved. Hoare had become involved in the debate and there were some very tricky questions to be answered.

Alley's letter goes on: "Rayner is attending to loose ends and will no doubt brief you on your return." We know that Rayner was with Yusupov the morning after the murder, and we also know he was with Yusupov at the station when Yusupov was arrested.

It is very difficult to see how anyone, given the analysis of the letter and the facts I have outlined above, cannot say that it provides primary evidence of British involvement and that the "accepted version" of the events was in fact a cynical conspiracy to pervert the course of justice.

The intelligence operations going on in the background were run by Alley, Captain John Dymoke Scale, the subsequent recruiter of Sidney Reilly, and another MI1c officer, Lieutenant Oswald Rayner, who had been sent out in November 1915 with Major Henry Vere Benet to carry out an extensive "censorship" of telegrams and mail examined in total collaboration with the Russian authorities, while sharing the intelligence it produced on a rather more selective basis. Some of the most productive material came on Scandinavian shipping companies taking goods into or out of Germany through the Royal Navy economic blockade.

German intrigue was becoming more intense daily. Enemy agents were busy whispering of peace and hinting how to get it by creating disorder, rioting, etc. Things looked very black. Romania was collapsing, and Russia herself seemed weakening. The failure in communications, the shortness of foods, the sinister influence which seemed to be clogging the war machine, Rasputin the drunken debaucher influencing Russia's policy, what was to the be the end of it all?

The key link between the British secret service bureau in Petrograd and the Russians plotting Rasputin's demise was Rayner through his relationship with Prince Yusupov, the leader of the Russian plotters. Yusupov enticed Rasputin to his family's palace on the banks of the river Neva in Petrograd for a "party", with the prospect of sex apparently high on the agenda. Yusupov told his wife Princess Irina, the Tsar's niece, that she was to be used as "the lure" to entice Rasputin to attend the party, a suggestion that appears to have persuaded her to extend a holiday in the Crimea so she was not in Petrograd at the time. Those known to have been present for the "party" in the Yusupov palace, apart from Rasputin, include Yusupov himself; the Grand Duke Dmitry Pavlovich, the Tsar's second cousin; Purishkevich; Lieutenant Sergei Sukhotin, a friend of Yusupov's; Dr Stanislaus de Lazovert, the medical officer of Purishkevich's military unit, who was recruited as the driver; plus Rayner.

Once there Rasputin was plied with drink and then tortured in order to discover the truth of his alleged links with a German attempt to persuade Russia to leave the war. The torture was carried out with an astonishing level of violence, probably using a heavy rubber cosh - the original autopsy report found that his testicles had been "crushed" flat and there is more than a suspicion that the extent of the damage was fuelled by sexual jealousy. Yusupov, who is believed to have had a homosexual relationship with another of the plotters, the Grand Duke Dimitri, is also alleged to have had a previous sexual liaison with Rasputin. Whatever Rasputin actually told the conspirators, and someone in his predicament could be expected to say anything that might end the ordeal, they had no choice then but to murder him and dispose of the body. He was shot several tunes, with three different weapons, with all the evidence suggesting that Rayner fired the final fatal shot, using his personal Webley revolver. Rasputin's body was then dumped through an ice hole in the Neva.