When Andrea Orcel was named as CEO-in-waiting at Santander last month, it was the crowning moment of a stellar six-year spell running UBS’s investment bank. Orcel, renowned as a consummate dealmaker, proved he was also a skilled operator with a knack for streamlining the business. His elevation to the top of the Spanish bank, Europe’s second largest lender, was just reward for a job well done.

But a Financial News investigation, which included interviews with a dozen current and former UBS executives, reveals another side to Orcel’s tenure at the Swiss bank, one marked by his volatile temper and a series of angry clashes with other senior staff, according to several people who worked closely with him.