Berkeley Group has seen its pre-tax profit climb 26% to £270.7 million over the year ending April 30 2013. The housebuilder sold 3,712 new homes against 3,565 over the same period in 2012 at an average selling price of £354,000 (2012: £280,000) due to changes in mix. Its operating margin lifted 1.6% to 20.4%. Over the period, Berkeley invested £314.6 …