Retail prices in Britain were up 10.6 percent in August compared to levels a year earlier, the highest rate of inflation since 1982, the government reported Friday. Higher prices for gasoline, heating oil, food and beer pushed the index up 1.0 percent between July and August, the Central Statistical Office said. The last time inflation was in double figures was in March 1982 when the rate was 10.4 percent. Excluding mortgages and local taxes, the rate of increase was 7.9 percent in August, up from 7.0 percent in July, the government said.