Scientists say they have worked out the formula for the perfect cup of tea - and say the key ingredient is patience. Researchers at the University of Northumbria said the key to the best tasting brew was to let it sit for six minutes before drinking. Not only does it avoid scolding but by then it has cooled to 60C, the optimum temperature to let the flavours flood out. But leave it until after 17 minutes and 30 seconds and the tea will be past its best, reports the Daily Telegraph. The team at the universitys School of Life Sciences spent 180 hours of testing and a panel of volunteers consumed 285 cups of tea in the laboratory. They concluded that the best method was to add boiling water to a tea bag in a mug and leave for two minutes. Then remove the bag and add the milk and leave for six minutes until it reaches optimal temperature of 60C. Ian Brown, senior lecturer at the University of Northumbria, said it was the complex taste of tea that made it so popular. DS