Of the four biographical films that Tacita Dean is showing at the National Portrait Gallery – David Hockney, Cy Twombly, Michael Hamburger and Merce Cunningham – I found the long, indeterminate film of Michael Hamburger in 2007, the year of his death, the most moving. Nor had I realised how important Hamburger was to an understanding of Sebald, a fellow émigré, who came to Britain with his family in 1933, settling first in Edinburgh, then London, then Hove, went to Westminster and Christ Church and began by translating Hölderlin. His desk, looking out onto orchards, shown in Dean’s film, appears in The Rings of Saturn and Dean made her film for an exhibition called Waterlog which was shown in Norwich Museum and the Sainsbury Centre in 2007. It shows Hamburger talking about the rare varieties of apple which he grew and picked.