Kelvin MacKenzie must rank as the most successful editor ever to work for Rupert Murdoch. He guided The Sun to its highest circulation and was responsible for many of its memorable iconic headlines. He regarded Murdoch, the man he affectionately called “boss”, as the world’s greatest newspaper owner. When the phone-hacking scandal broke in 2011, MacKenzie was among the most forthright supporters of Murdoch’s company. In the course of several TV and radio appearances, he echoed the News International line that a single “rogue reporter” had been responsible for voicemail interceptions. It has long been known that MacKenzie was deeply upset when the truth about the scale of hacking finally emerged. But he maintained a silence in public until his appearance on ITV documentary The Real Hack – the companion to a seven-part drama series, The Hack. He has now revealed just how angry he was to discover the fact that hundreds of people had been hacked by journalists working for the News of the World. He said: “I wrote a note to Rebekah Brooks …