There was a point when Paul McCann thought the phone might stop ringing. After 27 years in practice, including a long stint as managing partner of Grant Thornton Ireland, followed by a spell as chief executive of technology company Ergo, McCann could have moved into the world of non-executive roles. Indeed, he had already started the process. “The phone will stop ringing me at some stage, for everyone. You do get past your sell-by date at some stage,” he says. “I wondered when it might happen to me.” Then, last year, the phone rang. It was BGF, a private equity…