LONDON, July 15 (Reuters) - The number of employees on British company payrolls surged by 356,000 in June from May, the biggest increase since the start of the coronavirus pandemic, as the economy bounced back from its coronavirus lockdowns, tax data showed on Thursday. The headline unemployment rate for the three months to May rose to 4.8%, the Office for National Statistics said. Economists polled by Reuters had mostly expected the unemployment rate to hold at 4.7%.