And the full extent of the scams on the health service by Belfast solicitor George Brangam may never be known.

Brangam specialised in representing NHS organisations in medical negligence cases, and worked for 11 of the province's 23 trusts and boards.

He died last year while the subject of a major police investigation into fraud against health service clients.

A report published today by the Northern Ireland Audit Office revealed that his corruption has been traced back to 1998.

Twenty-seven different irregularities have been identified, involving a total of £277,652.

The bodies most affected were the Causeway Health Trust (12 cases valued at £120,727) and the Northern Health Board (five cases valued at £108,296).

Other victims included the Royal and Mater hospital trusts, the Ulster Community Hospitals Trust and the South and East Belfast Trust.

The £277,652 has been recouped by NHS organisations from Brangam's now defunct practice.

The Audit Office explained that the string of frauds included:

• skimming off interim payments from cases, which were not deducted from final settlement sums fixed at later dates
• overstating the size of settlements and keeping the difference
• falsely telling health service bodies that cases had been concluded and pocketing fake settlement payments
• receiving settlements on separate occasions in the same cases
• making claims for legal expenses that were either false or overstated.

The Northern Ireland Audit Office said that in one case a plaintiff's solicitor assisted Brangam by removing a settlement value from paperwork. It did not identify the lawyer involved.

Today's report detailed how chances to detect Brangam's activities were repeatedly missed over the years.

It also outlined a string of oversight failings by public bodies. These included not seeking evidence of actual settlement values and not obtaining acknowledgement of payments from plaintiffs.

In addition, Department of Health guidelines on monitoring court case settlements dating back to 1998 were not followed. These could also have led to Brangam being caught out much earlier.

"It is our view that opportunities for earlier detection of some of the fraudulent activities of George Brangam were missed," the report said.

The Audit Office said the uncovering of just one suspicious case would have been enough to trigger an investigation "which would have promptly terminated this long-running loss of public funds".

The £277,652 total was calculated by accountants appointed by the Department last year to review the files.

Of some 470 transactions examined, 79% were considered to be reasonable and 6% were deemed irregular.

In the remaining 15%, the accountants had insufficient information to make a judgment or case files were not available from either Brangam's practice or health bodies.

The Audit Office said this was "disappointing" particularly because the cases were a sample "and consequently other frauds may have occurred but not been identified".

The report also said: "There is a possibility that the extent of fraud committed by George Brangam was higher than determined by available evidence.

"However, the Department told us that the full position may be as stated and that it is not possible to establish categorically the level of fraud because some files, which might have clarified some issues, have been destroyed under routine and legitimate procedures."

It was the Causeway Trust, Brangam's chief victim, which raised concerns with the authorities in 2006 and prompted the major fraud investigation that ended his career.

These concerns involved a sum of £13,525 which the solicitor obtained in 2001 to settle a case. In fact, this case had not been settled and a member of Brangam's staff informed the Causeway Trust in 2004 that the plaintiff was proceeding.

Unsuccessful attempts to clarify the situation were made in 2004 but it was not followed up again until June 2006, when the Department raised a query.

The Audit Office said that while Causeway, like some other health bodies, had missed earlier opportunities, it is to be "commended" for uncovering Brangam.