It wasn't the most sophisticated of tax dodges - a small spiral-bound notebook with a kitten on the cover which was used to record under-the-counter payments to employees and sub-contractors.
But the "pussy book" kept by Ms Caroline Bailey, bookkeeper to Bovale Developments and wife of one of its directors, has an even greater significance in this tribunal, in that it constitutes a sort of "exhibit A" in the case against Mr James Gogarty.
In response to the allegations made against them by Mr Gogarty, the Bailey brothers have claimed they paid Mr Gogarty £162,000 for his help in securing the purchase of the Murphy-owned lands in north county Dublin. The money was paid in "dribs and drabs" and some of the amounts were recorded in Ms Bailey's "pussy book".
However, the flaws in this case were only too evident yesterday as Ms Bailey nervously gave evidence about her involvement in the brothers' business.
The book records payments of more than £94,000 in the year from April 1990, as well as three payments totalling £30,000 to Mr Gogarty.
As Mr Des O'Neill SC, for the tribunal, pointed out, the book recorded sizeable payments to the directors themselves as well as to other individuals. None of the payments was recorded in the company's books. Ms Bailey explained this was because she was working as a bookkeeper on the orders of the directors.
Mr O'Neill seemed unconvinced by the handwritten entries concerning Mr Gogarty. Most appear on the left-hand side of the book, away from the other entries. Most were written in black pen, when everything else nearby was written in blue.
Ms Bailey said the colour of the biro she used "signifies nothing".
But the "pussy book" - so named by Mr Michael Bailey, although Ms Bailey used the term "kitten book" - wasn't the only means the Bailey brothers had of channelling money to themselves.
A £50,000 cheque dated
September 7th, 1990, was made out to AIB Ltd but found its way into the personal account of Tom and Caroline Bailey. The witness said it was used to fund her husband's sheep farm in Co Meath.
However, the tribunal's investigations have so far failed to trace this payment. This is the cheque which was linked in the company's accounts to the Baileys' acquisition of the Murphy lands in north county Dublin.
But if it was used to buy sheep, it couldn't have been given as payment or security to Mr Gogarty. Ms Bailey's explanation therefore further discredits the claim by the Baileys that they gave Mr Gogarty two post-dated cheques for £50,000 each.
Other large cheques written to "cash" and to one Joseph O'Neill (unidentified) also ended up in the directors' personal accounts. Ms Bailey agreed with Mr O'Neill that it was "unusual" for directors to write company cheques which would end up in their personal accounts.
The witness said she just took the brothers at their word when they wanted a cheque drawn up.
"So they could have divided the cheque between themselves and put it on a horse," said Mr O'Neill.
"Yes; just because I was married to one of them didn't mean I had the right to interrogate them over a cheque," Ms Bailey replied.
It's doubtful how much more the tribunal will be able to add to its picture of Bovale's finances for the crucial 1989 period as most of the company's records were destroyed in a fire at the site office in Finglas in 1997, Ms Bailey revealed.
Considering that other accounts for this period were destroyed by water damage at its accountants' office in Co Kildare at around the same time, it would appear that Bovale is a most unfortunate company. And this isn't including the burning of Poppintree House, which was situated on one of the parcels of land bought from the Murphys.
Undeterred, Mr O'Neill sought copies of any computer printouts Ms Bailey might be able to offer, as well as details of Tom and Caroline Bailey's accounts, held by their personal accountant based in, of all places, Kinsealy.
Under threat of a subpoena, the Bailey lawyers agreed to give the tribunal access to these documents.
Ms Bailey's evidence took longer than anticipated and she will not be cross-examined until after her husband Tom comes to the witness-box today.
Meanwhile, Mr Justice Flood ended the day with a promise of longer sittings in order to speed up the proceedings.