Bob Diamond, one of the City's best-paid bankers, will take over as chief executive at Barclays on 1 January, three months earlier than planned.The current head of the company's investment banking arm, Barclays Capital (BarCap), was confirmed as the replacement for John Varley, who had planned to step down at the end of March, back in September."Over the last 3 months, John and Bob have made good progress in completing the transition," chairman Marcus Agius said. "John's view, with which I and the board agree, is that we are now ready to effect the hand-over. The speed with which the transition has been completed reflects the continuity in management and strategy that the succession provides."Chelsea fan Diamond had promised a "seamless transition" when the move was announced.Varley, boss of the high street bank since 2004 and the man who helped Barclays survive the financial crisis, will vacate the hot seat on New Year's Eve and become senior advisor on regulatory matters to Diamond and the Barclays board until the end of September.Diamond has run BarCap since 1997 when it was Barclays de Zoete Wedd (BZW). Taking the top job is a money-spinning move for the 59-year-old American. His basic salary rises to £1.35m a year plus another £3.4m in bonuses and £6.75m in long term, performance-based share incentives.