Few newspaper editors are remembered beyond their lifetimes, but David Astor of the Observer is a great exception to the rule. He converted a staid, Conservative-supporting Sunday paper into essential reading, admired and envied for the quality of its writers and for its trenchant but fair-minded views.

Astor grew up at Cliveden, the country house on the Thames which his grandfather had bought when he turned his back on New York, the source of the family fortune. His liberal-minded father was a constant support, but his relations with his mother, Nancy, were always embattled. At Oxford he suffered the first of the bouts of depression that were to blight his life; a lost soul for much of the Thirties, he became involved in attempts to put the British Government in touch with the German opposition in the months leading up to the war.

George Orwell had urged Astor to champion the decolonisation of Africa, and Nelson Mandela always acknowledged how much he owed to the Observer's long-standing support. A generous benefactor to good causes, he helped to set up Amnesty International and Index on Censorship. A good man and a great editor, he deserves to be better remembered.

A former publisher and the deputy editor of the Oldie, Jeremy Lewis has written three volumes of autobiography and biographies of Cyril Connolly, Tobias Smollett and Allen Lane, the founder of Penguin Books. Shades of Greene: One Generation of an English Family, was published by Cape in 2010.