The rap sheet mounts. We have known for some time that he received large chunks of money over an 18-month period while he was minister for finance and leader of the opposition. He has given at least three versions of the how, why and from whom this money came.

From records at his bank, we now know that his explanations don't stack up.

Would Gordon Brown survive that?

We know that Ahern, as a witness to the tribunal, contacted another witness to enquire about evidence that might be given. This places the Taoiseach in the dubious company of Pee Flynn, who rang Tom Gilmartin ahead of his evidence, and councillors who contacted Frank Dunlop, asking which beans he was going to spill.

The evidence about which Ahern contacted an AIB official concerned foreign-exchange transactions. For over a year until early 2007, Ahern and the bank failed to inform the tribunal of these transactions. Ahern has said he didn't recall the sterling lodgements but the bank was checking out foreignexchange transactions on his behalf in late 2005.

Failing to cooperate with the tribunal is a criminal offence. Proving to a criminal standard that Ahern was guilty of the offence would be very difficult, if not impossible. But the tribunal, and any notion of standards in public office, are not concerned with "beyond a reasonable doubt". The leader of a progressive democracy should be above reasonable suspicion in these matters and the records suggest Ahern isn't up there communing with the angels.

Let's just concentrate on the foreignexchange transactions. Let's give Bertie the benefit of the doubt about his tales of saving 50 grand in cash over seven years when he was strapped and the initial dig-out and further savings of �22,000 from a salary of around �50,000 in 1994. Let's just deal with what the records say.

On 11 October 1994, Ahern made a lodgement of �24,838.49 to his account in AIB O'Connell Street. This figure equates to stg�25,000 at that day's exchange rate. But Ahern says the deposit was made up of �16,500 from his second dig out and stg�8,000 from a whip-round in Manchester, where he wasn't appearing as minister for finance and where his prospective landlord Michael Wall drove the bus but didn't eat the dinner.

Plausible alternative explanation:

Ahern deposited one lump sum of stg�25,000 that day.

Supporting evidence: Records show the branch took in sterling to a value of �27,491.95 that day. This is a multiple of the average sterling bought by the bank on a daily basis at the time.

For example, for the previous four working days, the branch bought respectively the following amounts of sterling: �678.66, �3313.03, �610.84 and �1,510.15. For Ahern's account to be plausible, a mystery person must have coincidentally lodged at least stg�17,000 in the branch on the same day that he lodged his �8,000 Sterling. All this in a branch where the average daily sterling intake was around �1,500. The coincidence is possible, particularly if it was the only coincidence in this murky affair, but it's not.

On 5 December 1994, Celia Larkin lodged �28,772.90 in an account in her name at the branch. This, Ahern says, represented stg�30,000 the reluctant diner Wall gave him the previous Saturday in a briefcase at his constituency office. The money was, the Taoiseach says, to go towards refurbishment of a relatively new house, which Wall was due to buy and rent to him.

Coincidentally, the figure lodged equates to $45,000 on one exchange rate being used that day. Ahern and Larkin deny ever dealing in dollars.

Plausible alternative explanation:

Larkin lodged $45,000 rather than stg�30,000.

Supporting evidence: The branch's records show only �1,921.53 in sterling was bought that day, a long way short of stg�30,000. The records also show the branch remitted $45,000 to the currency services division of the bank on the day in question.

The official who dealt with Ahern's account has no recollection of Larkin arriving in with a suitcase stuffed with stg�30,000.

Maybe Bertie is the victim of another coincidence. Maybe another mystery person lodged $45,000 on the same day Larkin lodged stg�30,000 in a branch where the daily foreign exchange purchased equated to less than �2,000.

That still doesn't account for where the 30 grand went. Maybe some teller got his sums wrong. Maybe the tooth fairy snaffled the money and bought drinks for his buddies around the corner in Conway's.

Maybe.

Early the following year, Ahern says he decided to return to Wall the 30 grand sterling. He withdrew 50 Irish from his account and purchased 30 sterling with the intention of returning it to Wall, nice and neat in the currency in which he had received it in the first place.

Then he changed his mind. Instead, he put the money in his safe. In June, Larkin lodged the equivalent of stg�10,000 to her account and in December he lodged the remaining stg�20,000 in his.

Plausible alternative explanation:

There was no to-ing and fro-ing from his safe and exchanging currencies in the first half of 1995. Instead, the 10 and 20 grand sterling lodgements came from someone else unconnected with the now starving Wall.

Supporting evidence: The branch has no record of buying stg�30,000 in the first half of 1995.

So much for the sums. It could be that there is a major misunderstanding here and that there is an explanation for all these coincidences. If so, Ahern hasn't offered anything plausible in the accounts he has already furnished the tribunal and the public. Maybe fate has been terribly unkind to the most cunning of them all.

After that, we enter familiar tribunal territory of changing stories, poor memory and inappropriate contact between witnesses. AIB documents show that in October 2004 an official, Jim McNamara, was examining foreign-exchange documents as part of an inquiry by Ahern.

In 2006, accountant Des Peelo prepared a report on Ahern's finances in which the only sterling transaction recorded was the �8,000 alleged whip-round in Manchester. Is it plausible that Ahern, a trained accountant, couldn't remember large chunks of sterling going through his account until he was asked about it by the tribunal early this year?

His poor memory exacerbated the work of the tribunal. Earlier this year, the Taoiseach bemoaned how the tribunals "have now gone on longer than the two world wars". Is it any wonder if the level of cooperation afforded by himself and AIB is anything to go by? We are dealing here with the cream of the crop, the Taoiseach and a bluechip company. How much memory loss and blatant obstruction has the inquiry had to endure from those at the grubbier end of business and politics?

Earlier this year, Ahern telephoned McNamara. He wanted to know what documentation the bank had unearthed about three of the foreign-exchange transactions "so that when he would have to answer any questions, he would be aware of the same information that we had submitted to the tribunal", McNamara told the inquiry on Wednesday.

Sound familiar? Ahern knew the transactions had involved foreign currencies. Is it plausible, or likely considering everything we now know, Ahern was attempting to get his story to match the bank's ahead of any interviews with the tribunal?

The Fianna Fail reaction is also familiar. Ahern's legal team is attempting to propagate the notion that the tribunal has an agenda. On Newstalk 106 last Wednesday, Conor Lenihan pointed out the tribunal itself has been guilty of withholding evidence. Two weeks ago, a Sunday newspaper ran a story, apparently emanating from sources close to the Taoiseach, which suggested somebody was attempting to put money into his bank account without his knowledge. As the facts grow more unpalatable, the conspiracy theories get wackier.

Ahern's current difficulties are not down to the tribunal. They are writ large on AIB headed documents. Spinning against the tribunal or dark forces is a weak, transparent attempt to deflect from the unpalatable facts. The records don't lie.

The party mantra is redundant.

"Leave it to the tribunal" doesn't wash.

When Pee Flynn refused to explain his 50-grand present from Tom Gilmartin, the party didn't wait for the tribunal.

Flynn was censured in the Dail. And when his daughter refused to take the whip on the motion, she was ejected from the parliamentary party.

Where does the party hierarchy stand now? During the election campaign, Ahern held a crisis meeting with Brian Cowen, Micheal Martin and Dermot Ahern. He assured them there was nothing to worry about. Are they and their colleagues happy to continue spinning in the face of mounting facts? Is this what the party really represents?

When Ahern gives evidence in September, it will be a year since his money tales first blew up. The drip, drip has served him well. He has handled it with his customary, understated brilliance.

We could yet get to hear his latest version under public examination.

Maybe it's all just one big misunderstanding.