In 1910 Buchanan was appointed as the British Ambassador in Russia. His friend, Harold Williams, a journalist working for the Daily Chronicle, kept him informed of the political developments in Russia and arranged for his to meet some of the leading reformists in the country.
He reported back to London on the different reformers. He said of Irakli Tsereteli: "Tsereteli had a refined and sympathetic personality. He attracted me by his transparent honesty of purpose and his straightforward manner. He was, like so many other Russian Socialists, an Idealist; but though I do not reproach him with this, he made the mistake of approaching grave problems of practical policies from a purely theoretical standpoint." He was much more concerned about the possible impact of Victor Chernov, a leading figure in the Socialist Revolutionary Party: "Chernov was a man of strong character and considerable ability. He belonged to the advanced wing of the SR party, and advocated the immediate nationalization of the land and the division among the peasants awaiting the decision of the Consistent Assembly. He was generally regarded as dangerous and untrustworthy."
Buchanan became a much more important figure in Russia in the build-up to the First World War. He sent regular reports to Sir Edward Grey, the British foreign minister. In July 1914 he wrote about negotiations with members of the Russian government: "As they both continued to press me to declare our complete solidarity with them, I said that I thought you might be prepared to represent strongly at Vienna and Berlin danger to European peace of an Austrian attack on Serbia. You might perhaps point out that it would in all probability force Russia to intervene, that this would bring Germany and France into the field, and that if war became general, it would be difficult for England to remain neutral. Minister for Foreign Affairs said that he hoped that we would in any case express strong reprobation of Austria's action. If war did break out, we would sooner or later be dragged into it, but if we did not make common cause with France and Russia from the outset we should have rendered war more likely."
Buchanan also became very concerned about the influence of Grigory Rasputin who was against Russian involvement in the war. It has been argued that Buchanan became involved with the British Secret Intelligence Service in Petrograd, under the command Lieutenant-Colonel Samuel Hoare. Members of this unit included Oswald Rayner, John Scale, Cudbert Thornhill and Stephen Alley. Hoare became friendly with Vladimir Purishkevich and in November 1916 he was told about the plot to "liquidate" Rasputin. Hoare later recalled that Purishkevich's tone "was so casual that I thought his words were symptomatic of what everyone was thinking and saying rather than the expression of a definitely thought-out plan."
John Scale recorded: "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?" Michael Smith, the author of Six: A History of Britain's Secret Intelligence Service (2010) has argued: "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."
Grigory Rasputin was assassinated on 29th December, 1916. Soon afterwards Prince Felix Yusupov, Vladimir Purishkevich, the leader of the monarchists in the Duma, the Grand Duke Dmitri Pavlovich Romanov, Dr. Stanislaus de Lazovert and Lieutenant Sergei Mikhailovich Sukhotin, an officer in the Preobrazhensky Regiment, confessed to being involved in the killing.
Samuel Hoare reacted angrily when Tsar Nicholas II suggested to the British ambassador, George Buchanan, that Rayner, was involved in the plot to kill Rasputin. Hoare described the story as "incredible to the point of childishness". However, Michael Smith has speculated that Rayner was at the scene of the crime: "He (Rasputin) 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."
Buchanan began to fear that Tsar Nicholas II might be overthrown and urged him to bring in reforms. He reported on a meeting he had with the Tsar in January 1917: "I went on to say that there was now a barrier between him and his people, and that if Russia was still united as a nation it was in opposing his present policy. The people, who have rallied so splendidly round their Sovereign on the outbreak of war, had seen how hundreds of thousands of lives had been sacrificed on account of the lack of rifles and munitions; how, owing to the incompetence of the administration, there had been a severe food crisis." Buchanan urged the Tsar to take notice of what was being said in the Duma: "The Duma, I had reason to know, would be satisfied if His Majesty would but appoint as President of the Council a man whom both he and the nation could have confidence, and would allow him to choose his own colleagues."
Although a man of deeply held conservative views, Buchanan developed good relationships with liberal politicians in Russia during the revolution and welcomed the appointment of Prince George Lvov as head the new Provisional Government in Russia as he refused to withdraw the country from the First World War. He told the British government: "Lvov does not favour the idea of taking strong measures at present, either against the Soviet or the Socialist propaganda in the army. On my telling him that the Government would never be masters of the situation so long as they allowed themselves to be dictated to by a rival organization, he said that the Soviet would die a natural death, that the present agitation in the army would pass, and that the army would then be in a better position to help the Allies to win the war than it would have been under the old regime."
By the summer of 1917 Buchanan realised that the experiment in democracy was not working: "The military outlook is most discouraging. Nor do I take an optimistic view of the immediate future of the country. Russia is not ripe for a purely democratic form of government, and for the next few years we shall probably see a series of revolutions or counter-revolutions. A vast Empire like this, with all its different races, will not long hold together under a Republic. Disintegration will, in my opinion, sooner or later set in, even under a federal system."
Prince George Lvov was replaced by Alexander Kerenskyon 8th July, 1917. Buchanan reported back to London: "From the very first Kerensky had been the central figure of the revolutionary drama and had, alone among his colleagues, acquired a sensible hold on the masses. An ardent patriot, he desired to see Russia carry on the war till a democratic peace had been won; while he wanted to combat the forces of disorder so that his country should not fall a prey to anarchy. In the early stages of the revolution he displayed an energy and courage which marked him out as the one man capable of securing the attainment of these ends."
However, Buchanan, feared the growing support for the Bolsheviks: The Bolsheviks, who form a compact minority, have alone a definite political programme. They are more active and better organized than any other group, and until they and the ideas which they represent are finally squashed, the country will remain a prey to anarchy and disorder. If the Government are not strong enough to put down the Bolsheviks by force, at the risk of breaking altogether with the soviet, the only alternative will be a Bolshevik Government."
Buchanan was horrified by the Russian Revolution but recognised the talents of Vladimir Lenin and Leon Trotsky. In his book, My Mission to Russia and Other Diplomatic Memories (1923) he explained: "I readily admit that Lenin and Trotsky are both extraordinary men. The Ministers, in whose hands Russia had placed her destinies, had all proved to be weak and incapable, and now by some cruel turn of fate the only two really strong men whom she had produced during the war were destined to consummate her ruin. On their advent to power, however, they were still an unknown quantity, and nobody expected that they would have a long tenure of office."
George Buchanan died in 1924.