Paul Martin, former Prime Minister of Canada

Canada's former prime minister says the G20 should have a key role in trying to solve the world's financial problems. Paul Martin slashed Canada's budget deficit in the mid 1990s when he was finance minister, and as prime minister he advocated the establishment of the G20 and was it's first chairman.

Sarah Montague asks him what role he thinks the G20 should have and whether it is possible for member countries to do anything other than advance their own national interest.