By Guy Taylor The energy tycoon behind the £3.6bn takeover of Royal Mail’s parent company has pledged to turn the ailing postal service around or “go home”. Daniel Kretinsky, dubbed the Czech Sphinx, has dominated City chatter over the past few weeks after Royal Mail’s owner, International Distribution Services, waved through a takeover bid last week. However, he now has to convince investors he is the man to turn the troubled company’s fortunes around. Kretinsky’s bid values IDS at 370p per share and it now needs to be approved by 75 per cent of shareholders, with the billionaire already owni…