A bored policeman slouched over a dusty desk with two Soviet-era telephones is the only sign of life at the entrance to the grand Russian State Historical Archive on the banks of the Neva river in St Petersburg.

A typed note posted to the glass door informs a rare visitor that the archive is closed. Walking along empty echoing corridors of the former Senate, it is hard to imagine that this shrine of history is the cause of a scandal that has pitched the more conscientious members of Russia's intelligentsia against the Kremlin.