Philip Lynch faces the battle of his life on Wednesday to restore his reputation and see off a group of disgruntled investors at One51, the former co-op with investments in National Toll Roads (NTR), Irish Pride and Irish Continental Group (ICG), where he is chief executive.

Squaring up to Lynch is one of his former lieutenants, Gerry Killen, who invested €500,000 in One51 and was in charge of one of the company's divisions until a rift with the chief executive led to his departure in 2008. Killen has raised awkward questions for Lynch and the other members of the One51 board and has roped in several of the company's investors in a battle for a shake-up of the board at this week's annual general meeting.

Killen, who joined One51 after selling his business to Lynch, has attacked One51 on three fronts: its strategy, pay for top executives and transparency in its accounts. The rebel investor wants to rid One51 of its vast array of different businesses and focus on the waste-management division. He is seeking a board seat for himself, for businessman Alf Smiddy – the former Beamish & Crawford chief executive – and solicitor Peter Brennan.

One51, whose shares are traded on a grey market through several Dublin stockbrokers, owns a quarter of NTR, the renewable energy and toll roads group, a quarter of ICG, a stake in financial services firm IFG, breadmaker Irish Pride and a diverse range of waste and environmental companies. Killen says the company is too unfocused and has committed resources to too many investments. The lack of focus, he believes, has seen the value of One51 shares plunge from €3 a year ago to €1.75 by the end of last week. Getting the company back on track requires an orderly sale of these investments and for One51 to concentrate on becoming a waste management company, he said.

Attack dismissed

Sources close to One51 have dismissed Killen's attack on its investment strategy, pointing out that Killen's plan would see it spend money acquiring low-margin household waste-collection businesses rather than concentrate on more profitable sectors like the collection of hazardous waste and recycling. The sources also point out that the investments in NTR in the past have proved successful – with One51 receiving a hefty cash payment when NTR sold its stake in Airtricity – and that ICG, the ferry operator, is debt-free and paying dividends. It has also expanded further into the UK with the purchase of two hazardous waste companies for €18m.

As the Sunday Tribune reported last week, the company hopes that better results will persuade shareholders that its strategy is paying off. The results show earnings for the first six months of the year rose 14% to €26m and sales climbed 26% to €190m. The company is also thought to be confident that its net debt will fall again this year. Borrowings stood at just over €163m at the end of 2009.

In addition to providing more details on the first-half results, Lynch is expected to reiterate the company's plan for a "liquidity event", which could involve the payment of a dividend, a share buyback or a float of its environmental division.

More damaging to One51 is Killen's criticism of corporate governance, particularly payments to directors. In a detailed set of questions sent to the chairman Denis Buckley, he wants a breakdown of salary and bonus payments to individual directors. The company doesn't give details of payments. Executive directors earned €2.7m in 2009, according to its annual report. As it is not a publicly traded company, One51 does not have to disclose the individual payments.

Payments to executives

Killen has also put forward questions about payments to company executives routed through a company called Chandela. According to the list of questions sent to Buckley, Killen says a subsidiary of One51, Protech Performance Plastics, transferred intellectual property rights (about the design of a paint-tin lid) to Chandela in 2008. Protech then paid €4.96m to Chandela and he is demanding answers about the "commercial motives behind this" and "whether there is a corporate structure in place within the group in order to enable the payment of tax-exempt patent distributions to executives or companies in which executives have a material interest and which is designed to avoid proper and full disclosure of such payments".

While One51 has insisted the payment is compliant with tax law, it has given very few details about it.

One51 has remained remarkably silent on the attacks from Killen. According to a source familiar with the matter, Lynch met Killen in June at Dublin's Shelbourne Hotel to discuss his concerns. It is understood that a well-known businessman has been helping mediate relations between the two sides in recent months. Killen was offered a role with the company but refused it on the grounds that he would not be appointed to the board. Sources close to the company claimed Killen was seeking an unreasonable salary.

Lynch, the former chief executive of IAWS, probably has the numbers to see off Killen. Just over 50% of the company's shares are held by co-ops, including the Kerry Group Co-op and the UK's Co-Operative Society. While Killen is claiming the support of the latter, sources close to Lynch say he can count on the majority of Irish co-ops to support the board. About 20% of shares are held by directors and other employees and the rest by outside investors.

The showdown between the two sides at the annual general meeting is set for the Shelbourne Hotel.