Guardian: Tony Hayward, the under-fire chief executive of BP, has admitted for the first time that his job is on the line because of the Gulf of Mexico disaster. In an interview with the Guardian at BP’s crisis centre in Houston, Hayward also insisted that the leaked oil and the estimated 400,000 gallons of dispersant which BP has pumped into the sea to try to disperse the slick were relatively "tiny" amounts. "The Gulf of Mexico is a very big ocean. The amount of volume of oil and …