Documents obtained by the Sunday Independent reveal there was a series of intense meetings between the Department of Finance and Ireland's two biggest banks in the run up to the State guarantee.
The first took place at 10.40am on September 4 when two officials from AIB and Bank of Ireland met Mr Lenihan.
On September 8, two executives from AIB met William Beausang, a key civil servant in the department.
On September 18, AIB was again inside Merrion Street but this time it is unclear who they met.
Bank of Ireland met Gary Tobin of the budget, taxation and economic unit of the department on September 19 as part of a delegation that also included the company's big four auditors -- PWC, Deloitte, KPMG and Ernst & Young.
The big point of contact, however, was when AIB chairman Dermot Gleeson and CEO Eugene Sheehy and Bank of Ireland bosses Richie Burrows and Brian Goggin met Mr Lenihan and Taoiseach Brian Cowen again on the night of the guarantee -- September 29.
AIB has declined to comment on what was the purpose of its series of meetings with Mr Lenihan's department. It also declined to comment on whether it had lobbied for a State bank guarantee that in its case has cost the taxpayer €20bn.
Bank of Ireland, the Sunday Independent understands, was under considerably less pressure than AIB but it was fearful about the knock-on impact of either Anglo or its rival AIB failing.
On the night of the guarantee, and afterwards, it was supportive of the State playing a strong role in propping up the banking system.
For the first time, it has been confirmed that it was AIB and not Bank of Ireland that instigated the dramatic crisis meeting on the night of the guarantee -- This has been confirmed by two independent sources to the Sunday Independent.
Also, it has been confirmed that ministers not in Government Buildings that night were told that it was AIB and not just Anglo Irish that was in "immediate danger".
This information has not come out before now, as most people said that Anglo Irish was in trouble. It is believed that there was a concerted effort to protect AIB and Bank of Ireland at Anglo's expense.
AIB would not comment on whether it was it and not Anglo that the Government most feared might fail if some form of a guarantee was not introduced.
John Deasy, FG TD and PAC member, yesterday said that if it was the case that former ministers withheld key information from the public in relation to AIB, then the PAC must be given full powers to investigate.
"If it is the case that politicians and former ministers knew more than they previously admitted, then this inquiry needs to be given wide-ranging powers under legislation to investigate. Anything short of that will be futile," he said.