During Paul Tucker's questioning by the Treasury Select Committee, he said that concerns about Barclays' submissions existed at the time he spoke to Mr Diamond in October 2008 not only in Whitehall but also in the markets.
After the launch .co-ordinated international efforts to shore up the markets early in the month, both officials and markets were monitoring Libor and found that - compared to many other participants which had lowered their submissions - "Barclays continued to pay higher rates in the market".
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.