Feargal O’Rourke is clinging to the lectern, speaking a mile a minute and losing his train of thought. Throughout his career, he had delivered hundreds of presentations to political and business leaders, and provided counsel to high-powered boards, government ministers and multinational bosses. As a child, the young O’Rourke had even delivered speeches after communion in his local church in Athlone. On this occasion, however, O’Rourke is bristling with nerves. It is 2015, and the tax specialist is making his pitch to become the next managing partner of PwC, the professional services giant. He knows each of the 100 people…