THERE was a time when Digby Brown was the GMB’s go-to law firm in Scotland, handling all personal injury and industrial relations disputes for the trade union’s Scottish members.

That relationship fell apart two and a half years ago, though, and, as revealed by The Herald last week, the trade union is now pursuing Digby Brown for damages over what it alleges was negligent advice in relation to union members’ equal-pay claims.

In a mark of just how seriously the union is taking the case it has instructed Burness Paull – one of Scotland’s most expensive law firms – to fight its corner.

The rift between the GMB and Digby Brown dates back to 2015, when the union ousted its then regional secretary Harry Donaldson and replaced him with its national energy secretary Gary Smith, who at that time was a frontrunner to take over as the union’s general secretary.

There was a tacit understanding that the reshuffle was largely prompted by the union’s handling of equal-pay claims taken against a number of Scottish local authorities on behalf of the GMB’s members.

Those claims relate to a 2006 local authority pay review that sought to iron out historical disparities in the amount of money paid to men and women who were carrying out work of equal value.

A source close to the union said that when Mr Smith came on board “one of the first things he moved to do was ditch Digby Brown” because he felt “there had been poor advice around equal pay”.

At around that time he sent a letter to members employed by North Lanarkshire Council saying he had “launched a full investigation into the North Lanarkshire case and a complete assessment of the legal strategy pursued by Digby Brown in relation to our equal-pay cases in all of Scotland”.

“If claims need to be amended, they will be, and if we have received the wrong advice we will take action to protect our members’ position,” he wrote.

Perhaps unsurprisingly, his action coincided with the union itself being threatened with legal action from its own members, many of whom were disgruntled that the settlements they received from North Lanarkshire were lower than the payouts awarded to those represented by other parties.

The reason for that is that the GMB only sought compensation for the so-called pay protection element of the 2006 pay review, which allowed male workers to continue earning what they did before the review took place even though the bonus element of their pay had been abolished.

In addition to arguing that payment protection discriminated against women, fellow union Unison and claims firm Action 4 Equality Scotland demanded that staff be compensated for the outcome of the review itself, which they argue was also discriminatory.

“One of the big, difficult legal arguments that is still ongoing is that if you didn’t challenge the Workforce, Pay and Benefits Review you can only use a comparator under the new scheme, not the old,” Stefan Cross QC of Action 4 Equality Scotland said.

“Previously a home carer would have been on the same grade as a refuse-lorry driver.

“In the new scheme a home carer would be on grade three but a driver on grade five [meaning] the council said the work stopped being of equal value.

“That makes a huge difference to the amount of money being claimed.”

The GMB had filed claims against Glasgow City Council on the same basis, but after the Court of Session found against the local authority in two related cases last year, in November it filed new claims that also challenged how members’ grades were reassessed.

The problem is that because the pay-protection period ran from January 2007 to March 2009 and equal-pay claims can only be backdated for five years, the 2,000 women the GMB represents in Glasgow will not be able to claim compensation for the two and a half years between March 2009 and November 2012.

While that could potentially leave the union open to action from the Glasgow claimants, its case against Digby Brown makes it clear its position is that it was acting under the advice of its legal advisers.

Indeed, a spokesperson for the GMB confirmed that the union has “commenced court proceedings against Digby Brown in relation to advice given on equal-pay claims”.

A spokesman for Digby Brown said that as the case is now live the firm could not comment on the matter beyond saying that it intends to defend itself against all elements.

With the case, which has just been filed at the Court of Session, expected to last for a considerable length of time, a source close to the matter said that ultimately it is the women who are affected that could stand to lose out.

“The difficulty for the claimants is that they are caught between a rock and a hard place if the GMB says it was Digby Brown’s fault and Digby Brown says it was the GMB’s fault,” the source said.