The premiership of his successor, Sir Edward Heath was the bloodiest in the history of the Northern Ireland Troubles. He was prime minister at the time of Bloody Sunday in 1972 when 14 unarmed men were killed by British soldiers during a banned civil rights march in Derry. In 2003, he gave evidence to the Saville Inquiry and claimed that he never promoted or agreed to the use of unlawful lethal force in Northern Ireland. In July 1972, he permitted his Secretary of State for Northern Ireland William Whitelaw to hold unofficial talks in London with a Provisional Irish Republican Army delegation by Seán Mac Stiofáin. In the aftermath of these unsuccessful talks, the Heath government pushed for a peaceful settlement with the democratic political parties. In 1974, the Sunningdale Agreement was produced but fiercely repudiated by many Unionists and the Ulster Unionist Party ceased to support the Conservatives at Westminster.