As the Imperial War museum marks its centenary, it is making public the very personal mementoes from its first collection.

The museum was set up in 1917 to create a memorial for a war that was still being fought, and so families sent in their personal letters and photographs of relatives who had fought and died.

The modern Imperial War Museum also reflects World War Two and includes the Cabinet War Rooms, where Winston Churchill worked underground while London faced Nazi air raids.

Joy Hunter, now aged 91, tells Sean Coughlan for BBC Radio 4's The World at One about working as a secretary in that strange subterranean world.