Great-nephew of Alfred Flechtheim, who was forced to flee the Nazis, is frustrated at slow progress in returning works by Picasso and Klee

German experts have long agreed that Michael Hulton, the sole surviving heir to an illustrious Jewish art collector forced to flee the Nazis, has a strong case for restitution. But after years of waiting, he’s running out of patience – and time.

Hulton, 78, is the great-nephew of Alfred Flechtheim, a pre-eminent cultural figure of the “Roaring Twenties” whose refined taste for the avant garde and infectious enthusiasm made him a tastemaker of early 20th-century Germany.