ROBERT BARRLONDON (AP) ¿ Compass Group PLC, the world's largest food service company, on Wednesday said profit rose 33 percent in the first half of its financial year, largely on the strength of improved margins. The company said its net profit for the six months ending March 31 was 287 million pounds ($438 million), compared to 216 million pounds a year earlier. Revenue rose 24 percent to 6.9 billion pounds on a reported basis, and 2.6 percent on a comparable basis. Compass Group shares were up 8.2 percent at 360 pence in morning trading on the London Stock Exchange. Julian Cater, analyst at Collins Stewart, said the underlying operating profit of 455 million pounds was ahead of the consensus of 425 million pounds. "The key driver of this was margin improvement," Cater said. "On a reported basis, margins increased by 0.8 percent to 6.5 percent, and on an underlying basis the margin improvement was 0.6 percent, slightly ahead of management's 0.5 percent pre-close guidance."