By Bethany Wales From an unknown tech start-up to the undisputed king of the UK’s online property sector, Rightmove is a shining example of how to turn a simple idea into a whole lot of profit. In its most recent full-year results, the London-listed property portal astounded investors by revealing it had achieved a record 71 per cent operating profit margin – by far the highest seen on the market in recent years. The impressive margin is far higher than its closest peers, Auto Trader (55 per cent), Hargreaves Lansdown (52 per cent ) and data giant Relx (30 per cent). So, how has Rightmove mana…