By Frank Dalleres Sir Jim Ratcliffe has declared his minority investment in Manchester United the most exciting experience of his varied career in business and sport. The British billionaire founded and still runs chemicals giant Ineos, and has taken his brand into Formula 1, road cycling, America’s Cup sailing and international rugby union. But he says the deal to buy 25 per cent of boyhood club United from the Glazer family, subject to Premier League ratification, has eclipsed his previous ventures. “I have done a few exciting things, but this caps it all. There’s no question about that,” Ra…