Twenty years ago last August, I was asked by an associate of Denis O’Brien to meet the telecoms and media entrepreneur at Dublin Airport in a tiny lounge tucked away from the regular terminals. “Bring your passport just in case,” I was told, as O’Brien might be airside.  When I got there O’Brien was sitting by himself in an empty lounge, in the private-jet terminal. His gleaming plane was not far behind him, being refuelled ahead of the long flight to Kingston, Jamaica where his telecom business Digicel was headquartered. I was there to be interviewed for the job as…