JOHN McGuinness, the chairman of the Public Accounts Committee, has long been happy to be portrayed as the Steve Silvermint of Irish politics: the cool, clean hero tackling waste, excess, mismanagement and inefficiency in the public sector; a straight talker who pulled no punches and avoided no toes that required stepping on.
But his credibility on that score has taken a bit of a dent in recent weeks. First came the revelations in the Irish Independent that, while he was a junior minister at the Department of Enterprise, €290,000 was spent on renovating his ministerial office.
And then this newspaper also revealed that his son, Andrew, was paid €30,800 in overtime – on top of his €42,000 salary – in one year for his role as personal secretary to Mr McGuinness, who was then a junior minister.
It is important to stress that there is no suggestion of any wrong-doing by Mr McGuinness (or, indeed, his son). He has said he had no part in the costing or fit-out of his office, merely approving a broad outline of the plans. And, in relation to his son's pay, he claimed it would "correspond" to what was paid to other people working for ministers and TDs.
However, it is fair to submit that Mr McGuinness has fallen short of the high standards he routinely demands from the Government and the public service.
He may not have had any involvement in the upgrading of his office, but given his commendable quest for value for the taxpayers' money, shouldn't he have asked about the cost of the plans?
He would presumably have been aware of the "gold-plating" criticism that accompanied other upgrades/refits of state offices. Such a no-nonsense operator should arguably have made it his business to ensure his own office was not going to be another example of this.
The overtime earned by his son does not appear to "correspond" with that paid to other ministerial staff. It seems to have been the highest in the past six years. Eamon O Cuiv's staff, for example, received no overtime payments.
Comparisons aside, by any reasonable assessment, overtime payments of €48,000-plus and mileage of €13,334 – the supplemental amount paid to Andrew McGuinness during his two years employed by the Department of Enterprise – are not good value for money for the taxpayer. In one of the years, Andrew McGuinness's additional overtime pay – an eye-watering €30,800 – was the equivalent of almost two-thirds of his salary. That gave him a combined income of €72,800.
John McGuinness is far from the only politician to employ a family member as a secretary or an assistant. But he is supposed to be different.
That is the key point about these revelations. Mr McGuinness has not broken any rules or laws. What has emerged does not make him a bad politician or his position as PAC chairman untenable.
However, it opens him up to the public perception that he is little different from the rest in Leinster House.
For years, Mr McGuinness's popularity with the public, and indeed the media, has been very much about his being "different".
He was the Fianna Fail deputy not afraid to own up to his party's mistakes. The public-serving TD/minister with a private sector ethos. The no-nonsense hard man calling it as it is.
It was these characteristics that made him the obvious candidate to chair the Public Accounts Committee.
Not everybody in the Dail is quite so enamoured now, including certain members of his own party. Some claim he plays to the public gallery – a case of more style than substance. But they do respect his acumen and his understanding of PR.
These qualities still mean that Mr McGuinness has plenty to offer as committee chairman.
He must, however, rebuild his credibility as the chief watchdog on public expenditure. He won't do that with conspiracy theories about attempts to discredit him or talk of "powerful people" trying to nobble his bank inquiry.
He will do it by concentrating on the nuts and bolts of his job. And by admitting that, while he did not do anything wrong on these two occasions, he failed to ensure that the high standards he demands of others were met.
Shane Coleman is Political Editor of Newstalk 106-108FM.