Britain's employers reined in their hiring and posted fewer job vacancies in April, according to data on Tuesday which showed the impact of the Iran war on the economy and prompted investors to cut their bets on Bank of England interest rate hikes. Early payroll data from the tax office - often revised sharply around the start of the tax year in April - showed a heavy fall of 100,000 in the month from March, and estimates for the previous four months were lowered.