Guido has been given documents coming from inside Anglo Irish Bank’s Treasury Department dating back to 1997 which strongly suggest there was a board level approved conspiracy to over-charge corporate customers. The scale of the fraud was massive and it may have contributed up to 10% of the now nationalised bank’s profits.

The Anglo-Irish Bank’s fraud comes from overstating the DIBOR base rate on which customer’s loans were calculated. DIBOR is the Dublin Interbank Offered Rate, calculated and published daily like LIBOR, it was set in stone and used by all Irish banks as the basis for settlement of trades and financial transactions before they joined the Euro.

Essentially Anglo-Irish lied to customers as to what that the real base rate was by adding between 1/4% to 1/3% to the official underlying rate, then they added the usual banker’s spread that they will have agreed contractually with their corporate customers.

Guido’s source says that inside Anglo-Irish the false rate quoted to borrowers was known internally as “TIBOR” after Tiarnan O’Mahoney, the Director and Chief Operating Officer to whom Des Whyte, the treasury manager who prepared the figures, reported. Sources say that the “TIBOR” version of “DIBOR” was not used with sophisticated money market customers who would have queried the rate.

Guido has done some back of an envelope calculations based on the bank’s 1999 Annual Report. The customer loan book is reported to have been €5.7 billion (IR£4.4 billion). Assuming that only half the clients were over-charged the average of 30 basis points the bank will have made an extra €8.6 million, (IR£6.6 million) on the bottom line. That was some 10% of the bank’s reported profits.

According to a source the fiddle continued throughout the late 90s into the early half of the next decade as Anglo-Irish’s loan book grew on the back of the Celtic tiger. Customers could have been ripped off by as much €100 million.

N.B. Guido has documentation to back up this story – if the Dublin authorities want it…

UPDATE : There was an error with the graphic illustration above earlier which has now been corrected to show the correct corresponding date.