Sidney George Reilly (; c. 1873 – 5 November 1925), fictionalized as the "Ace of Spies", was a Russian-born adventurer and secret agent employed by Scotland Yard's Special Branch and later by the Foreign Section of the British Secret Service Bureau, the precursor to the modern British Secret Intelligence Service (MI6/SIS). He is alleged to have spied for at least four different great powers, and documentary evidence indicates that he was involved in espionage activities in 1890s London among Russian émigré circles, in Manchuria on the eve of the Russo-Japanese War (1904–05), and in an abortive 1918 coup d'état against Vladimir Lenin's Bolshevik government in Moscow.
Reilly disappeared in Soviet Russia in the mid-1920s, lured by the Cheka's Operation Trust. British diplomat and journalist R. H. Bruce Lockhart publicised his and Reilly's 1918 exploits to overthrow the Bolshevik regime in Lockhart's 1932 book Memoirs of a British Agent. This became an international best-seller and garnered global fame for Reilly. The memoirs retold the efforts by Reilly, Lockhart, and other conspirators to sabotage the Bolshevik Revolution while still in its infancy.
The world press made Reilly into a household name within five years of his execution by Soviet agents in 1925, lauding him as a peerless spy and recounting his many espionage adventures. Newspapers dubbed him "the greatest spy in history" and "the Scarlet Pimpernel of Red Russia". The London Evening Standard described his exploits in an illustrated serial in May 1931 headlined "Master Spy". Ian Fleming used him as a model for James Bond in his novels set in the early Cold War. Reilly is considered to be "the dominating figure in the mythology of modern British espionage".
The true details about Reilly's origin, identity, and exploits have eluded researchers and intelligence agencies for over a century. Reilly himself told several versions of his background to confuse and mislead investigators. At different times in his life, he claimed to be the son of an Irish merchant seaman, an Irish clergyman, and an aristocratic landowner connected to the court of Emperor Alexander III of Russia. According to a Soviet secret police dossier compiled in 1925, he was perhaps born Zigmund Markovich Rozenblum on 24 March 1874 in Odessa, a Black Sea port of Emperor Alexander II's Russian Empire. According to this dossier, his father, Markus, was a doctor and shipping agent, while his mother came from an impoverished noble family.
Other sources claim that Reilly was born Georgy Rosenblum in Odessa on 24 March 1873. In one account, his birth name is given as Salomon Rosenblum in Kherson Gubernia of the Russian Empire, the illegitimate son of Polina (or "Perla") and Dr. Mikhail Abramovich Rosenblum, the cousin of Reilly's father Grigory Rosenblum. There is also speculation that he was the son of a merchant marine captain and Polina.
Yet another source states that he was born Sigmund Georgievich Rosenblum on 24 March 1874, the only son of Pauline and Gregory Rosenblum, a wealthy Polish-Jewish family with an estate at Bielsk in the Grodno Governorate of Imperial Russia. His father was known locally as George rather than Gregory, hence Sigmund's patronymic Georgievich. The family seems to have been well-connected in Polish nationalist circles through Pauline's intimate friendship with Ignacy Jan Paderewski, the Polish statesman who became Prime Minister of Poland and also Poland's foreign minister in 1919.
According to reports of the tsarist political police, the Okhrana, Rosenblum was arrested in 1892 for his involvement in political activities and for serving as a courier for a revolutionary group known as "the Friends of Enlightenment." Escaping judicial punishment, he became friends with Okhrana agents, such as Alexander Nikolayevich Grammatikov, and these details might indicate that he was a police informant at a young age.
After Reilly's release, his father told him that his mother was dead and that his biological father was her Jewish doctor, Mikhail A. Rosenblum. Distraught by this news, he faked his death in Odessa harbour and stowed away aboard a British ship bound for South America. In Brazil, he adopted the name Pedro and worked odd jobs as a dock worker, a road mender, a plantation labourer, and a cook for a British intelligence expedition in 1895. He allegedly saved both the expedition and the life of Major Charles Fothergill when hostile natives attacked them. Rosenblum seized a British officer's pistol and killed the attackers with expert marksmanship. Fothergill rewarded his bravery with 1,500 pounds sterling, a British passport, and passage to Britain, where Pedro became Sidney Rosenblum.
However, the record of evidence contradicts this tale of Brazil. Evidence indicates that Rosenblum arrived in London from France in December 1895, prompted by his unscrupulous acquisition of a large sum of money and a hasty departure from Saint-Maur-des-Fossés, a residential suburb of Paris. According to this account, Rosenblum and his Polish accomplice Yan Voitek waylaid two Italian anarchists on 25 December 1895 and robbed them of a substantial amount of revolutionary funds. One anarchist's throat was cut; the other, named Constant Della Cassa, died from knife wounds in Fontainebleau Hospital three days later. The French newspaper L'Union Républicaine de Saône-et-Loire reported the incident on 27 December 1895:
A dramatic event occurred on a train between Paris and Fontainebleau.... On opening the door of one of the coaches, the railway staff discovered an unfortunate passenger lying unconscious in the middle of a pool of blood. His throat had been cut, and his body bore the marks of numerous knife wounds. Terrified at the sight, the station staff hastened to inform the special investigator who started preliminary enquiries and sent the wounded man to the hospital in Fontainebleau.
Police learned that the physical description of one assailant matched Rosenblum's, but he was already en route to Britain. His accomplice Voitek later told British intelligence officers about this incident and other dealings with Rosenblum. Several months prior to this murder, Rosenblum had met Ethel Lilian Boole (later Voynich), a young Irish woman who was a budding writer and active in Russian émigré circles, allegedly while Rosenblum was staying in Lviv. The couple developed a rapport and began a sexual liaison, and he told her about his past in Russia. After the affair concluded, they continued to correspond. In 1897, Boole published The Gadfly, a critically acclaimed novel whose central character was allegedly based on Reilly's life as Rosenblum. In the novel, the protagonist is an illegitimate child who feigns suicide to escape his illegitimate past and then travels to South America. He later returns to Europe and becomes involved with Italian anarchists and other revolutionaries.
For decades, certain biographers had dismissed the Reilly-Boole liaison as unsubstantiated. However, evidence was found in 2016 among archived correspondence in the extended Boole-Hinton family, confirming that a relationship transpired between Reilly and Boole around 1895 in Florence. Whether he was genuinely smitten with Boole and sincerely returned her affections or he might have been a paid police informant reporting on her activities and those of other radicals remains unknown.
Reilly continued to go by the name Rosenblum, living at the Albert Mansions, an apartment block in Rosetta Street, Waterloo, London, in early 1896. He created the Ozone Preparations Company and peddled patent medicines. He became a paid informant for the émigré intelligence network of William Melville, superintendent of Scotland Yard's Special Branch. Melville later oversaw a special section of the British Secret Service Bureau founded in 1909.
In 1897, Rosenblum began an affair with Margaret Thomas (née Callaghan), the young wife of Reverend Hugh Thomas, shortly before her husband's death. Rosenblum met the Reverend Thomas in London through his Ozone Preparations Company because Thomas had a kidney inflammation and hoped for a miracle cure peddled by Rosenblum. Thomas introduced Rosenblum to his wife at his manor house, and they began an affair. On 4 March 1898, Hugh Thomas altered his will and appointed Margaret as an executrix; he was found dead in his room on 12 March 1898, just a week after the new will was made. A mysterious Dr. T. W. Andrew, whose physical description matched that of Rosenblum, appeared to certify Thomas's death as generic influenza and proclaimed that there was no need for an inquest. Records indicate that there was no one by the name of Dr. T. W. Andrew in Great Britain around 1897.