By Iain Mansfield In announcing a suite of planning reforms in her first speech as Chancellor, Rachel Reeves has addressed the biggest barrier to growth in Britain today, says Iain Mansfield The new Chancellor is serious about growth. By putting planning front and centre of her first speech, Rachel Reeves addressed the single biggest obstacle to economic growth in the UK today. As Policy Exchange demonstrated in Homes for Growth, increasing house building by 100,000 homes a year could add £17.7bn to the UK economy. Yesterday, the Chancellor laid out not just ambitions, but a series of tangible…