The Green Party's debut on the government stage was always likely to be fraught, but when the Greens entered into coalition on the arm of a confident if jaded-looking Bertie Ahern, they could not have predicted how the shape of government would change over such a short time.

This time last year they were just over a month into a new partnership, with the slick Drumcondra boy having been replaced by the mild-mannered midlands man, who was about as likely to smile for the cameras as Ahern was to turn down a lucrative contract as a sports columnist for a tabloid paper. The Greens were just adapting to the radically new approach to the management of government business when the economic situation began to unravel dramatically. By year end, the banks were lurching towards the disaster that is now well documented and construction was about to give way under the strain of economic failure and a lack of capital.

Dan Boyle was always something of a maverick. He had played an important role in the Greens' negotiating team on the formation of this government and, while he was deeply disappointed not to have won a seat in the Dáil, he determined then and there that he would have a seminal position not just in the formation of the new government but in the conduct of its affairs. He is half PJ Mara and half Pee Flynn – mercurial, skilful and Machiavellian. Using Boyle as a barometer of the mood in the senior ranks of the Greens has up to now been at best questionable.

So to last week's shenanigans: There are issues for government to face up to and the controversy around the banking system is one of them. Numerous investigations are under way, covering how the system generally performed, the kind of scrutiny provided by the regulatory bodies, and the performance in particular of Anglo Irish Bank, some of its executives and its board.

I have said before that these matters deserve due attention; the public has a right to expect that the various reviews will produce answers and practical decisions that will help the economy in the future, root out and punish any deliberate wrongdoing and create a platform for higher standards from now on.

I have argued here before that achieving this will take time. The balance between expediting the work of the various bodies carrying out the reviews and getting the right outcome is not easily achieved, but Dan Boyle's call last week for a further investigation into banking practices over the past decade could actually undermine a lot of the progress made to date.

The purpose of any investigation should be to establish where wrongdoing occurred, who was responsible and how they should be dealt with. That is at the heart of the work already under way. The Boyle view is that there should be a much wider review running in parallel. This would seem to be driven by the belief that Fianna Fáil, property developers and elements in banking were all in cahoots, which is why development lending was allowed to run so high. What is worrying for Cowen, Lenihan et al is that Boyle's call has more backing from the senior ranks of the Green party than in the past.

The race by Labour leader Eamon Gilmore to back Boyle and to increase the pressure on the government was, according to my sources, based on that belief. Gilmore has chosen his moments for combat more carefully than others and he believes the Green resolve is weakening.

On the face of it, Gilmore and Boyle appear to have a point. The problem is that unless you believe there was something corrupt involved, any such review would simply establish what we already know – that there was a failure of stewardship within the banks and a complete failure of the regulatory system to pick this up. A review of the banking system is not required to establish these facts.

It is likely that Boyle believes the looseness that appears to have permeated the sector and its regulatory authorities was due to institutional (and indeed national) arrogance.

What is afoot here seems to be party politics, with the Greens trying to establish a basis to position themselves for an exit from government. Boyle and his senior colleagues may well argue that this is the only credible basis on which to exit what they see as a contaminated administration. By making the case for this broad review of lending practices, and increasing the whiff of corruption, the Greens could justifiably walk out of government and precipitate a general election.

If you believe that, bad and all as things are, the last thing this country needs now is an election, then this has to be worrying. The junior party in government may now believe that this is its last chance to put some distance between its own virtue and Fianna Fáil's pragmatism. If this view gains currency, as I fear it will, then the senior people in the Greens will feel forced to put the needs of their party ahead of the needs of the country.