Tens of thousands of Iranians took the streets of Tehran on Thursday to mark the 31st anniversary of the Islamic Revolution. The rallies were attended by large numbers of government security forces who were there to prevent any protest by the opposition green movement. Maziar Bahari is a Canadian-Iranian journalist who has been Newsweeks Iran correspondent for the last 10 years. Last year he was imprisoned in Tehran's notorious Evin Prison for 118 days. He joins Sir David from New York.