Six weeks after the St Patrick's Day massacre in 2008 that sent Anglo Irish Bank's stock down 15%, developer Liam Carroll's North Quay Investments told the Dublin Docklands Development Authority that the bank wanted even more space for its new headquarters building on the north docks.

The bank had blamed "false and misleading" rumours about its financial strength for the share price fall but it appears to have been deluding itself, even if the share price had already regained the losses by the time Carroll, his son Conor and his lieutenant, David Torpey, met the DDDA at its headquarters on 30 April to inform the authority of the bank's request for additional space.

The share price increase was a false dawn. The bank seems to have had no idea of what was coming, as it had told Carroll it was seeking an additional 40,000 square feet on top of the headquarters building – the equivalent of two additional floors over the entire building – which it was funding. If the extra two floors had been occupied it would have cost about €2m a year to rent just that portion of the building from Carroll, according to a senior industry source, which the state would now be on the hook for.

The DDDA's director of architecture, John McLaughlin, said the building's parapet height under the proposed new planning scheme "would remain the same" apart from a tower element and this "could be configured to deliver the required space", according to minutes of the meeting which have been seen by the Sunday Tribune.

Carroll was also in talks with AIB Capital Markets at the time about renting one of its buildings, and wanted to raise the height of the building to 110 metres, nearly twice the height of Liberty Hall. Torpey asked whether they needed to lodge a new application "in relation to this proposed development".

The developer was also in talks with Bank of Ireland regarding proposed lettings of three other blocks he wanted to let to the bank. One had been earmarked as a hotel, but this was being "reviewed in light of Bank of Ireland's current space requirements" which "would represent employment figures of approximately 8,000 people" between the three buildings.

In effect, Carroll was planning to create a domestic financial services centre next to its international equivalent and had spent a reported €250m buying land for it. In the end, though, the collapse of global banking, combined with poor lending decisions by the Irish banks, meant that none of the buildings was completed.

The Anglo building in particular became a shambles. The future of the half-completed structure rests on a decision by An Bord Pleanála, which has been considering for nearly a year whether it can be retained or should be demolished. The initial planning permission granted by the DDDA for the building was ruled "ultra vires" in October 2008 after a court case taken by rival developer Sean Dunne; a subsequent decision by Dublin City Council to allow the building to be completed led to the appeal to An Bord Pleanála.

By November of that year Sean Dunne's Mountbrook had approached the DDDA seeking arbitration in its judicial review. Then DDDA chief executive Paul Maloney and Carroll's Royceton indicated "they would not be availing of this", according to documents seen by the Sunday Tribune. Dunne had gone to the courts seeking to have the building torn down. That case was adjourned pending the outcome of his planning appeal.

The failure to complete the building was one of the main reasons Carroll's Zoe Group empire ended up in receivership.

Anglo has since appointed McStay Looby to look after its part of the building. Sources say the bank can walk away from the lease for several reasons including the fact that it hadn't been completed within a specified time limit.

The bank is considering its options but industry experts believe it will eventually take the building back, complete it and move in before disposing of it in a sale and leaseback deal.