In a surprise statement issued barely an hour before the former Barclays boss Bob Diamond was due to appear before the Treasury select committee, Tucker requested an audience with the committee to put his side of the story.
In the Commons, prime minister's questions was dominated by the row between the government and Labour over whether the inquiry into the banking crisis should be conducted by a joint parliamentary committee or a judge.
In a Commons session dominated by the banking scandal, David Cameron condemned the "spivvy and probably illegal" activity in the banking rate-fixing scandal.
He said it was "outrageous" that homeowners may have been forced to pay higher interest rates as a result of efforts to rig the benchmark Libor and Euribor rates, but flatly refused to back Labour's calls for a judge-led inquiry into the culture of the City.
The role of Tucker in the interest rate fixing scandal is expected to be the subject of scrutiny when Treasury select committee MPs meet Diamond on Wednesday. Barclays has issued a memo in which Diamond made a record of a conversation he had with Tucker during the 2008 banking crisis and which led to some confusion in the bank about whether the central bank was encouraging Barclays to cut its Libor submissions – figures supposed to represent the interest rate at which banks are willing to lend to one another.
When Barclays was fined a record £290m by regulators in Britain and the US last week for attempting to manipulate the price of Libor – the London interbank offered rate – one of the elements of the fine related to attempts by Barclays to lower the rate during the crisis to avoid any impression that the bank was in financial difficulty.
The regulatory documents show that Diamond did not interpret that conversation with Tucker as a signal that Barclays should cut its Libor submission. But the Barclays banker Jerry del Missier apparently interpreted the memo written by Diamond as clearance to reduce the submission – which led to the bank cutting its rates.
Del Missier's resignation was announced on Tuesday, hours after Diamond's departure in the wake of political pressure. Diamond ran Barclays Capital, the investment banking arm of the bank, at the time of the offences – which took place between 2005 and 2009 – while Del Missier was also a senior figure at BarCap. Diamond was promoted to chief executive in January 2011; Del Missier to chief operating officer only two weeks ago.
The memo written by Diamond – and sent to the then chief executive John Varley and copied to Del Missier – implied Tucker was receiving pressure from Whitehall figures to tackle Barclays' relatively high interest rates. The identity of those Whitehall figures is not yet clear.
Lady Vadera, the economist who advised Gordon Brown and was made a minister, denied that she had spoken to Tucker about Libor rates.
She also rejected claims that she authored a Treasury note titled Reducing Libor, but insisted it dealt with entirely legitimate government concerns.
"I did not have a conversation with Paul Tucker about Libor," she told BBC Radio 4's The World at One.
"I did not have the conversation that is being alleged and I didn't write that note.
"I commented on the note, in particular to focus the issues on the lending conditions in the real economy for real people."
Asked if anyone in the Labour government had suggested to the Bank of England that the rate should be manipulated, she said: "I can only speak for myself. I can't obviously speak for everybody in government.
"You asked me if Libor was a concern and of course it was a concern. There is nothing wrong with concerning yourself with access to credit. That's the job."
But that concern "cannot be confused or used as an excuse for the actions of traders who choose, for their own reasons and for their own book, to do certain things", she added.
In the Commons the prime minister said it would be "inexplicable" and wrong if top bankers who were forced out or quit as a result of scandals received "a vast payoff".
Amid reports that Diamond could be in line for a payout of up to £22m, Cameron was urged by fellow Conservative Sir Peter Tapsell to ensure "the delinquents are not able to walk away with their bonuses and severance payments".
Cameron told MPs: "I think it would be completely wrong if people who were leaving under these circumstances were given some vast payoff. It would be completely inexplicable to the British public and it would not be right, and I very much hope that doesn't happen."
The prime minister said the government would legislate so that all pay deals were put to shareholders in a binding vote "and those deals should include any severance payments".
Earlier in the day, the deputy prime minister, Nick Clegg, bemoaned the fact that Diamond would not be "short of a bob or two", despite leaving the bank under a cloud.
Clegg said: "I think many people will be dismayed, as he's leaving under a cloud, that he might be paid handsomely, he'll get handsome rewards for having presided over serious wrongdoing."
While there appeared to be cross-party consensus against payoffs, the deadlock over the nature of the inquiry that should be held into the failures of banking continued as Cameron underlined his preference for a "swift and decisive" parliamentary inquiry over Labour's call for a judge-led independent investigation.
Ed Miliband told the prime minister across the dispatch box that his reluctance to set up an investigation along the lines of the Leveson inquiry into media practices showed he did not understand the scale of public concern over the banking scandal.
The Labour leader used prime minister's question time to set out a proposal for a two-stage inquiry, with an initial investigation into Libor rigging completed by Christmas and then a wider 12-month investigation of the culture and practices of the City.
Miliband said: "The banking scandal of the last week has revealed traders cheating, the mis-selling of insurance products to small businesses and comes on top of other scandals in the banking system and the continuing multimillion bonus merry-go-round."
He asked the prime minister: "How can you convince people that a parliamentary inquiry is a better way of restoring people's confidence than a full, independent, forensic and open judge-led inquiry?"
Cameron argued the need for a swift inquiry into what he described as an "appalling" scandal.
"People want to know that crime in our banks, crime in our financial services, will be pursued and punished like crimes on our streets," he said.
"I think as well as people being held accountable, they want rapid action to make sure this cannot happen again. In my view the most important thing about an inquiry is that it is swift and decisive, set up as fast as possible, gets going as fast as possible, reports as fast as possible, transparent and open at every stage.
"That's why I favour a public, parliamentary inquiry rather than a judge-led inquiry. I want us to legislate on this, starting next year."
But Miliband said there were concerns that a parliamentary inquiry would be "far too narrow" in its focus on the Libor rate "when we know the problems go much wider to the culture and practices in the City".
Cameron said he would look at the proposal for a two-part inquiry but added: "On the issue of the structure of banking and the future of banking, we set up the Vickers inquiry which reported and we are going to implement the Vickers inquiry which will, for the first time, separate investment banking from retail banking. It's a major step forward.
"Second point: the inquiry, the parliamentary inquiry we are proposing, is wider than you say. It is going to look at the culture of banking."
He added: "Clearly, the Serious Fraud Office are still considering whether to launch a criminal investigation.
"While that's happening there are dangers in opting for a judge-led inquiry which might not be able to get under way."
The parliamentary inquiry was the best way to "get action as fast as possible", he said.
Labour's call for a judge-led inquiry was rejected in a vote in the Lords by 251 to 197 on Tuesday. But in an attempt to force the issue further, Cameron announced that MPs would be asked to vote on Thursday on either setting up a judicial inquiry or a joint parliamentary inquiry of peers and MPs, as proposed by the government.
Cameron threw down the gauntlet to Miliband to back the parliamentary inquiry if MPs voted in favour of it, but the Labour leader did not respond to the challenge.
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