Should we celebrate Russian Revolution art?

On entering a new exhibition of Russian art at the Royal Academy in London you are greeted by stunning images of Soviet culture paintings, films and textiles - but also by portraits of Joseph Stalin.

Why is it acceptable to display pictures of one dictator responsible for the deaths of millions of people but not another - Adolf Hitler?

Military historian Sir Antony Beevor and Guardian art critic Jonathan Jones discuss on the World at One the apparent pitfalls of exhibiting such works from the Russian Revolution.