(Reuters) - British infrastructure company Balfour Beatty Plc reported higher first-half underlying pretax profit and increased its annual cash forecast on Wednesday, buoyed by lower costs and higher margin projects. Balfour Beatty, which operates through its "Build to Last" operating programme, has been selecting lower risk contracts to focus on generating cash and profitability in a sector that has won less work since the Brexit referendum in June 2016. The FTSE 250 listed company increased..