Mulcahy had to resign his Aer Lingus post in 2004 because of "tax issues", but today he is chairman of the new Dublin Transportation Authority (DTA), the allpowerful body charged with getting the capital moving again.

It is the DTA which, along with the old Rail Procurement Agency unwillingly swallowed into its embrace, will oversee the building of the new metro, Luas extensions, as well as the introduction of new bus routes and a long-awaited unified ticketing system Given Dublin's appalling infrastructural problems, its daily gridlock and the resultant financial and environmental costs to the nation, it is hard to envisage a more difficult and challenging job - and certainly one deserving of the highest calibre candidate to fill it.

Mr Mulcahy's credentials as a banker and a business strategist are not in doubt.

Under his charge, AIB was hugely profitable; with former pilot Willie Walsh installed in the chief executive seat, he helped to turn Aer Lingus from loss into profit.

But the fact that he had tax issues, due to what he later said involved several hundred thousand euro in an offshore account, at a time when every last penny was needed to pay for underfunded health, education and transport services, remains a real issue.

Mr Mulcahy has since settled with the Revenue Commissioners, but he has never revealed exactly what the "tax issues" which led to his resignation were. All we know is that they emerged during an investigation into the AIB's handling of overseas accounts and relate to a period when Mr Mulcahy worked for the bank in Britain. Although Mr Mulcahy's tax issues did not relate to the AIB's offshore scheme, it operated under his charge and, as Senator Shane Ross told the Senate during the week, the bank ended up "being forced to pay a fine of Euro90m in respect of a period for much of which he had been in charge of it."

Some would argue that Mr Mulcahy has paid his due and that the transport problems are so dire we can't afford to deny a man of his calibre the chance to sort them out.

But if this is the case, then the government should have met the obvious questions about Mr Mulcahy's tax record head on. They should have issued a statement clarifying all outstanding issues and explained clearly why, if Mr Mulcahy had to resign in 2004 from Aer Lingus, he is a suitable candidate for the chairmanship of the extremely powerful DTA in 2007.

This government's continued inability to realise the seriousness of tax evasion by the super-rich - and the involvement of banks in facilitating them - when others were paying punitive rates, undermines their claims to transparency and equality in the operations of the state.

Transport minister Martin Cullen may have suggested Mr Mulcahy for the position, but the entire cabinet - including its PD members Michael McDowell and Mary Harney - have ratified the appointment without a quibble. The PDs are full of surprises, not all of them welcome.

The fact that no cabinet member sees any need to explain this decision is a sign of the arrogance that comes with 10 years in power.