Syphilis killed Russian revolutionary Vladimir Lenin and not a stroke, believes a British historian.

To find the evidence, Helen Rappaport delved deep into books, papers and obscure journals.

Rappaport thinks the Soviets tried hard to cover up the real reasons for Lenin’s erratic, manic behaviour, bouts of rage and untimely death at 53, seven years after the revolution of 1917, reports The Daily Express.

In a bid to reach the conclusion, Rappaport unearthed comments from Professor Ivan Pavlov.

Pavlov said the “revolution was made by a madman with syphilis of the brain”.

The historian also cites a comment by Soviet diplomat Vatslav Vorovsky. He told an Italian colleague in Rome in the early1920s: “We are led by a schoolmaster whom syphilis has endowed with a few sparks of genius before it kills him.”

According to the historian, Lenin may have caught the disease from a prostitute in Paris in about 1902.

From 1921’s end he suffered a series of catastrophic physical attacks leading to progressive paralysis.