When the famous Russian writer Vladimir Nabokov died in 1977, he made it clear in his will that a manuscript he was working on should not be published.

In fact he instructed his wife Vera to burn the unfinished work.

Vera didn't destroy the work or publish it.

It was kept safely locked away in the vaults of a bank in Switzerland.

Now, more than 30 years after his death, Nabokov's son Dmitri has sparked controversy by agreeing to have his father's unfinished last novel The Original of Laura published.

So what was it that made Dmitri defy his father's expressed wish?

"It was prompted by the fact that he had turned 75," says Tatiana Ponomareva, the director of the Nabokov Museum in St Petersburg.

She is one of several Nabokov scholars who successfully convinced Dmitri to publish the manuscript.