In a plot twist worthy of John le Carré, we reveal the grandfather of the brilliant new head of MI6 was a Nazi spy chief, writes the Daily Mail.

“Archives in Germany reveal that the woman who from September will take charge of the nation’s secrets is the granddaughter of a notorious Nazi collaborator who spied and killed for Adolf Hitler’s Germany.

We can disclose that Ms Metreweli’s grandfather was Constantine Dobrowolski, a Ukrainian dubbed “The Butcher” who defected from the Red Army to become the Fatherland’s chief informant in the region of Chernihiv in Ukraine.

While Ms Metreweli never met her paternal grandfather – who remained in Nazi-occupied Ukraine while the rest of his family fled the Soviet “liberation” of the region in 1943 – his story does cast an awkward shadow over her impeccable career in MI5, MI6 and the Foreign Office.

The Mail has unearthed hundreds of pages of documents held in archives in Freiburg, Germany, detailing the extraordinary – and blood-soaked – life and times of Dobrowolski which are themselves worthy of a spy thriller. Known as “Agent No 30” by Wehrmacht commanders, he had vowed revenge against the Russians ever since they slaughtered his noble land-owning family, plundered their estate and seized Ukraine after the 1917 Bolshevik Revolution.

The archives detail how the Soviets put a 50,000-rouble bounty – £200,000 in today’s money – on the head of the local spy chief they labelled “the worst enemy of the Ukrainian people”.

Within the files are handwritten letters from Ms Metreweli’s grandfather to Nazi superiors signed off “Heil Hitler”. Shockingly, Dobrowolski boasted to German commanders of “personally” taking part “in the extermination of the Jews” and killing hundreds of Ukrainian resistance fighters. There are even accounts of him looting the bodies of Holocaust victims and laughing at the sexual assault of female prisoners”, - reads the article.