Paul Tucker will face questions from members of the Treasury Select Committee today about an alleged conversations he had with Bob Diamond and politicians about rigging the Libor rate.
Mr Tucker has been the Deputy Governor of the Bank of England since early 2009. He has been widely-tipped as the most likely successor to the current governor Mervyn King.
He joined the the Bank of England after graduating from Cambridge University in 1980 and has headed a number of divisions within the bank. Since 2002, he has served on the bank's Monetary Policy Committee, which has the responsibility of setting interest rates.
Today, he will be questioned about how much the Bank of England - one of the City's main regulators - knew about Libor rate-rigging, and why he appeared to imply that Barclays should lower its rate in an alleged phone conversation with Bob Diamond in 2008.
Bob Diamond tonight angrily rejected suggestions that he misled MPs over regulators' concerns about activities at Barclays.
The Bank of England's Paul Tucker told MPs he refuted claims that he attempted to influence Barclays into manipulating the Libor rate.
MPs will be hoping the Deputy Governor of the Bank of England will shed some light on unanswered questions about rate-fixing at Barclays.