Rosamund Bartlett readily admits to being intimidated by the subject of her latest biography. “It would be impossible not to be intimidated by Tolstoy,” she says with a wry smile.

“My biggest challenge was overcoming my fear. Tolstoy had this huge ego and took himself very seriously. I found that as a personality, he takes up the whole space, never wants you to get the better of him. There’s a sense in which you will never be able to pin him down, be equal to him.”

Whether she has pinned down the great Russian writer or not, she has certainly managed to map out his life with aplomb: in Tolstoy: A Russian Life, she charts his beginnings as an aristocrat born to great privilege, who found pleasure in drinking, gambling and pursuing peasant girls. After fighting in the Crimean War, he began writing about his experiences; no longer a dissolute youth, he was an artist with potent ambitions. War and Peace, written in his thirties, was to launch him into the literary firmament. As he got older and his family expanded ever more (he had 13 children by his long-suffering wife Sonya, five of whom died), his fame swelled to colossal proportions. He became a uniquely influential voice in Russia, in spite of his decidedly eccentric views in his final years.

“What surprised me most about him was the attention he gave to education,” she said. A former academic, the author taught Russian literature and cultural history at Oxford University before leaving to become a full-time writer. “After writing War and Peace, he put together this ABC book for children: from this great epic about world history, he went back to the alphabet. He also tried to emancipate his own serfs before an official act was passed in 1861 — his peasants were so uneducated they didn’t realise that they were working for his benefit; he was so shocked by that. He was a remarkable man. He was a social activist as well as a great novelist.”

While War and Peace and Anna Karenina are each individually proclaimed by many to be the greatest novel ever written (they are certainly two of the longest), some decry Tolstoy’s long-windedness, even dare to accuse the giant of world literature of being slightly boring. “Russia is a country of big dimensions,” she said. “Everything is on a big scale. Tolstoy thought in those terms. And he was incredibly competitive. He thought most European novel writing was a bit amateur. If you were going to write a novel, it had to be the biggest and the best; so War and Peace is this monstrous epic, but its vastness is part and parcel of what it is.”

She wrote almost all her biography from Oxford, relying on the Slavonic section of the Taylor-Bodleian library for her research (she says that the number studying Russian literature these days in Oxford is small; Tolstoy’s great-great-great-granddaughter, as it happens, is doing a doctorate on Nabokov but is the only person in her year).

Bartlett grew up in Surrey, started learning Russian at 14 and fell in love with the great Russian writers as an undergraduate at Oxford. Her previous book was a biography of the dramatist and short-story writer Chekhov. “Tolstoy was much more difficult,” she says. “Chekhov had far less of an ego. Chekhov is a much funnier, more playful, subversive man. There are not that many laughs with Tolstoy.”

Chekhov’s admiration for Tolstoy set Bartlett on the path to his biography: “Chekhov remained in awe of Tolstoy as this great moral authority and I wanted to understand that.”

Last month was the centenary of Tolstoy’s death. One might think this cause for great celebration in his native Russia, but the country remains ambivalent towards him and festivities have been low-key. Bartlett covers Tolstoyism in the 20th century in the epilogue — possibly the most fascinating section. She describes how Tolstoy was exalted into Soviet Russia’s canon of great (officially acceptable) writers, with his later transformation to vegetarian pacifist and Christian anarchist downplayed.

“Tolstoy has become tarred by the brush of Soviet propaganda,” she said. Officialdom does not know how to deal with someone who was excommunicated, a pacifist and vegetarian. “Nor is he in line with the Russia promoted by Putin: the very macho image,” she said She believes modern Russia is a highly commercial culture where there is no emphasis on great novels. “It requires a new generation to be able to approach Tolstoy again, with fresh eyes.”

* Tolstoy: A Russian Life is published by Profile at £25.