Mohamed ElBaradei, director general of the International Atomic Energy Authority, tells our diplomatic editor, Julian Borger, that existing agreements on nuclear non-proliferation are out of date.
Senior political commentator Michael White explains the likely effect on forthcoming elections of a week of revelations about MPs' expenses.
Two 56-year-old women have learned they were switched at birth and raised by each other's family. Ed Pilkington reports from New York.
Arctic explorer Pen Hadow describes his mission to find out how climate change is affecting the polar ice cap.
And Paul Drummond, biographer of Texan psychedelic rock band the 13th Floor Elevators, explains why he thinks they are worth celebrating 40 years after their demise.
