Heffernan personifies the combative corporate culture of Dunnes

Whether it is with workers, unions, disgruntled former managers, rivals, banks or landlords, Dunnes Stores is a magnet for conflict.

Margaret Heffernan, its battle-hardened chief executive, neatly personifies its corporate culture. She rarely backs down in a fight.

One way to assess the retailer's propensity for strife is its track record at the High Court. Over the past five years, Dunnes has been named as a defendant in 448 cases, way ahead of its similar-sized rivals SuperValu and Tesco.

Over the same period, Dunnes has initiated just 29 cases as plaintiff. Its opponents, overwhelmingly, initiate the lawsuits, suggesting that the retailer frequently adopts an intransigent approach.

A 2011 case against Dunnes, taken by Larry Howard, its former head of finance, revealed much about Heffernan's confrontational style. Howard reported to Andrew Street, Dunnes' former chief operating officer, who subsequently left for Superquinn.

According to Howard’s court affidavits, Heffernan considered him an “Andrew man” and froze him out, while making veiled threats to sack him. He claimed she had a tempestuous management style and was once heard to complain she wanted “either f***ing men or mice” to help her run the business.

That case was later settled, while a separate one taken by Street over his departure terms hasn’t progressed since 2011.

Among recent commercial rows, Dunnes was accused of trademark infringement by the Kerry Group in a row over Cheestrings; Aldi sued it over a price-comparison advertisement; a Nama-backed property developer took action against it over an unpaid €21 million debt; and there have been myriad disputes with landlords and developers over rent and leases.

The stubbornness of Dunnes' top management is also illustrated by an infringement case taken by the Karen Millen fashion business, which went all the way to the European Court of Justice in 2014. Dunnes lost.

Mandate, the union that organised yesterday's strike action, says Dunnes is "the most difficult" retailer with which it has ever dealt. It does not negotiate with trade unions and doesn't usually show up at Labour Court or Labour Relations Commission hearings.

Heffernan was always known in Dunnes as something of a union-buster. The retailer has been in several high-profile disputes, such as the 1980s anti-apartheid strikes or the 1995 strike that shut it down for more than three weeks.

Retail sources say Heffernan’s philosophy is encapsulated in a rejection of any outside interference in how the company is run, whether it be from unions, politicians, lawyers or lobby groups.

As for its ability to better reward workers, Dunnes is in a struggle for market share with Tesco, SuperValu and the German discounters. Dunnes is currently third largest in the grocery trade, with 23.4 per cent.

The company does not speak to the media and has unlimited status, so a veil of secrecy hangs over its finances. However, its total food and non-food revenues are estimated within the industry at about €3.5 billion.

Its British operations, which file accounts, most recently reported pretax profit margins of close to 10 per cent. If that multiple were applied across the group Dunnes could be generating earnings of more than €300 million annually.

Heffernan is surely well aware of the damage a prolonged strike could do to its bottom line.