U.S. President Barack Obama (R) meets with British conservative party leader David Cameron at Winfield House, the U.S. ambassador's residence in London April 1, 2009. World leaders will have their work cut out at a G20 summit where Obama makes his first major international sortie, under perhaps more pressure than anyone to show that the country where the crisis began can lead the way out. REUTERS/Jason Reed (BRITAIN POLITICS BUSINESS)