It's the end of an era at Merrill Lynch. John McNiven, the firm's colourful co-head of global debt markets in London and arguably the most successful debt market professional of the 1990s, is heading east to Hong Kong, to become co-head of Asian investment banking.McNiven's London replacement will be Anders Bergendahl, most recently head of relationship management and business origination in the investment banking group.It's a tough act to follow. McNiven, an ebullient Australian who drives a Rolls-Royce sporting the number plate MC NIV, joined the firm in 1988 from JP Morgan, along with six others, at a time when Merrill languished in 21st place in the Euromarket league table. But it topped the table in 1994 and has been there ever since.McNiven established a reputation as a straight-talking, innovative debt market practitioner.According to one colleague: "Tales about John are far too many to recount." One story concerns the run-up...