Hartmut Dorgerloh: Where do colonial treasures belong?

The Humboldt Forum is one of Germany’s great cultural institutions, housing a collection of thousands of works of non-European art. Germany, like many former imperial powers, is now asking itself whether treasures grabbed by European colonisers should be returned to their countries of origin. Stephen Sackur interviews the director of the Humboldt, Hartmut Dorgerloh. Is Germany taking the lead in the restoration movement?