Yuri Davydov, 67, fnally proved that he is Stalin's grandson. Picture: Wikipedia, Komsomolskaya Pravda

There have been rumours for years but now science has provided the proof with a 99.98% certainty. 'All I wanted is to protect the good name of my grandmother and parents,' he said, after the positive DNA result.

Members of his family had been accused of being 'imposters' for years, he said. 'I have been long prepared for this analysis and am pleased that (Stalin's) official family finally decided to take this step forward.'

A direct and official Stalin grandson Alexander Burdonsky - eldest son of Vasily Stalin, son of the former Soviet dictator - provided the crucial genetic material.

Lidia Pereprygina (Davydova) was married to another man and decided not to remember about Stalin. Picture: Boris Ilizarov

Yury Davydov's grandmother Lidia Platonovna Pereprygina, born in 1900, lived with Stalin at the age of 14 when he was exiled to Siberia. She had already given birth to one child by the future Soviet leader, when she was 15. The baby died.

But she became pregnant again in 1916 and gave birth to a boy after Stalin had left his exile. The boy was named Alexander. Later - when he ruled the Kremlin - Stalin would order a probe into the fate of a son he knew he had.

Alexander was registered in 1917 - the fateful year of the Bolshevik Revolution - as being Davydov's son. He had two children, and Yury - a retired construction engineer from Novokuznetsk, is his sole survivor. Picture: Boris Ilizarov

The investigation was conducted by an official called P Sirotenko who found that there had been a rumour Stalin had died at the front in the First World War. A local man Yakov Semenovich Davydov proposed to Lidia and she married him.

'Only four years later when she was shown Stalin's portrait in a newspaper did she she recognise her son's father,' said Sirotenko. 'But as she was married now to another man, she decided not to remember him.'

Yuri Davydov holds the copy of P Sirotenko's investigation. Picture: Larisa Maksimenko/Kuzbass85

Alexander was registered in 1917 - the fateful year of the Bolshevik Revolution - as being Davydov's son. He had two children, and Yury - a retired construction engineer from Novokuznetsk, is his sole survivor.

'In the early 1970s, when I was about 20, my mother and father invited me to a room for a 'serious conversation',' he remembered. 'They closed the door and told me everything.

A direct and official Stalin grandson Alexander Burdonsky - eldest son of Vasily Stalin, son of the former Soviet dictator - provided the crucial genetic material. Picture: Kultura

'But, of course, they immediately asked not to blab about this, to keep everything in confidence. A few years earlier the same conversation had hapened with my elder brother, Eduard, now deceased. How did I take this? Pretty easily - the world did not turn upside down.'