"I think there will be consolidation, " said Paul Keenan of BDO Simpson Xavier. Outside of the "big four" accounting firms . . . KPMG, PricewaterhouseCoopers, Deloitte and Ernst & Young . . .

few can offer the breadth of expertise necessary to fulfil the audit and accounting requirements of large corporate clients, according to Keenan.

"For the other mid-tier firms, consolidation is probably inevitable to get the range of services that they require, " he said. BDO is the fifth largest accounting firm in Ireland, ranked by annual fee income, according to the annual accountancy survey published in the current issue of Finance Magazine.

Keenan said BDO would continue to focus on its core market: mid-size companies and family-owned businesses. For firms with ambitions of taking a slice of the action away from the big four, however, Keenan said joining forces would be the most likely road to success.

Dublin-based Farrell Grant Sparks, ranked seventh by the survey, saw its fee income climb by almost 80% to 24.8m over the last year following its merger with Belfast 's McClure Watters and Longford's Lyons Keenan Kilemade.

Previously FGS had been in advanced negotiations with Mazars, the eighth-largest firm in Ireland , but the two decided not to proceed with a merger.

Despite the jostling for position among the middle tier accounting firms, the gap between the big four and the rest is huge. KPMG, PwC, Deloitte and E&Y account for over 70% of the market in Ireland, between them. E&Y, ranked fourth in the Finance survey with fee income of 117m, earned as much as the next three Irish firms combined.

Across Europe and the US, the big four act as auditors for the vast majority of publicly-quoted companies. The fact that such a large share of the audit work for major corporations in such a small number of hands is a topic of much debate both within the accounting profession and in the wider business community.

EU internal markets commissioner and former Irish finance minister Charlie McCreevy recently voiced his worry at the consequences for European business if one of the big four ran into difficulty.

McCreevy pointed to the demise of Anderson in the wake of its role as auditor to corrupt energy giant Enron as a cautionary tale for the industry.

"There is a possibility that some enormous claim could bankrupt the big four, but then who is going to take on that area of work? When Andersen went, the others firms took up the slack but there is no guarantee that if another one went that would be able to happen, " he said.

"Four firms controlling the public securities market is not enough. There's a gap there and there is an opportunity, " said Pearse Farrell of FGS.

Farrell said FGS' main priority continued to be mid-size firms but that he could see opportunities to take on the big four in the medium term.

Times are changing, said Farrell, and larger enterprises are already beginning to farm out some of their work to firms outside the traditional elite group of auditors. Joe Carr, managing partner of Mazars Ireland said Mazars International, of which the Irish firm is a full member, currently acts as an auditor to "about 15% of the top 300 companies in Europe".

The large Ftse 100 and Iseq constituents that traditionally relied on the big four are more inclined to look outside the cosy club in the postEnron environment, said Carr.

"I think the market is recognising that there is an imbalance there. Over time, I think, you'll see that balance being redressed slightly, " he said.

In the meantime, Mazars has beefed up its presence by acquiring Tierney & Co in Galway in 2004 and OJ Kilkenny earlier this year.

The 21 firms polled by Finance Magazine had combined income of 902.9m last year, up just under 18% on 2005. The big four accounted for 73.5% of that figure, down slightly on the 75.7% market share they enjoyed the previous year.