Presented by John Humphrys and James Naughtie. Liberal Democrat MP Evan Harris discusses why he feels the laws governing succession need to change. Chairwoman of Ofqual Kathleen Tattersall looks at what can be done to ensure that GCSE science standards are improved. Correspondent Kim Catcheside speaks to a woman who is facing eviction because her landlord is in mortgage arrears. A Queen's University academic has conducted research that concludes that crabs can feel pain. Professor Bob Elwood explains how he made this discovery. Gordon Brown is visiting Brazil ahead of the G20 summit in London. Political editor Nick Robinson speaks to the prime minister about what he has achieved during the visit, and his hopes for the G20. The Metropolitan Police has warned bankers that there is likely to be disruption caused by anti-capitalist protestors during the G20 summit. Reporter Jack Izzard gauges the reaction in the City. Schools Minister Jim Knight discusses whether science GCSEs are too easy. Thought for the day with Sir Jonathan Sacks. There will be an inquiry into claims that an MI5 officer was complicit in the torture of ex-Guantanamo detainee Binyam Mohamed. Correspondent Frank Gardner and former Attorney General Lord Goldsmith discuss the investigation. Gordon Brown has been in discussions with Buckingham Palace over possible reforms to the laws of succession. MP Chris Bryant discusses the implications for the monarchy. Colin Duffy, a high profile Republican in Northern Ireland, has been charged with the murder of two soldiers shot dead at Massareene Barracks in Antrim. Correspondent Mark Simpson reports. Former Environment Minister Michael Meacher and Fraser Nelson, the political editor of the Spectator, discuss whether bankers have been unfairly demonised. Housing Minister Margaret Beckett explains what the government can do to protect tenants who face homelessness if their landlord's property is repossessed. Former CIA member Emile Nakhleh and Michael Semple, former head of the EU mission in Afghanistan, discuss whether foreign forces are contributing to the unrest there. Harold Varmus, author of The Art and Politics of Science, discusses the history of the relationship between politics and science in the US. Lord Rees-Mogg discusses how changes to the laws of succession could be implemented. Roy Clare, the chief executive of the Museums and Libraries Association, has said members of boards and governance of many of Britain's cultural and creative organisations are 'male, stale and pale'. Mr Clare discusses his comments with Sir Christopher Frayling, former chairman of the Arts Council.