On a cloudy New York morning last October, Larry Diamond made his way up to the 42nd floor of Morgan Stanley’s headquarters near Times Square.

With former treasurer and US ambassador Joe Hockey by his side, the 40-year-old co-founder of Zip Co walked along a corridor where portraits of America’s captains of industry lined the Mahogany-panelled walls. He was there to meet another Australian, and another finance chief executive, but one that had reigned over Wall Street for longer than a decade.