At the High Court last week, Govia Thameslink Railway (GTR), the parent company of Southern rail, failed to secure an injunction against Aslef, the train drivers’ union. On Monday they took the case to the Court of Appeal, which also dismissed it, allowing the first drivers’ strike in the company to go ahead on Tuesday.

Southern, Britain’s worst-performing railway, has faced fierce opposition to its attempts to make drivers take on all the skilled operational duties currently carried out by guards. The company says driver-only operation – already in use on 60 per cent of GTR services – is perfectly safe. Unions say it isn’t, especially with increased passenger numbers, and fear it will lead to onboard staff being stripped out altogether.

Govia argued at the High Court that this week’s strikes infringed fundamental freedoms enshrined in the Treaty on the Functioning of the European Union. Govia is partly owned by Keolis (UK) Ltd, a subsidiary of the French company Keolis SA. Govia’s lawyers said that the French firm’s freedom of establishment in the UK under article 49 of the treaty would be restricted by the strikes.

According to Govia, a strike would also restrict the freedom of passengers to provide services to nationals of other EU countries, protected under article 56. Southern serves Gatwick Airport, and ‘37 per cent of air passengers using Gatwick Airport use rail to get to and from the airport, which is the highest proportion in the UK. Without that rail service operating, Gatwick Airport will be extensively impacted, as will the rights of those involved.’

Aslef’s lawyer, Oliver Segal, said the court would be playing with fire if it upheld this argument. It would mean that London Underground drivers ‘could call a strike on the Jubilee Line because it does not intersect with King’s Cross, Gatwick or Heathrow, but not on the Piccadilly Line,’ he said. ‘There are countless comparable situations that must be arising every day.’

Govia’s barrister, Hugh Mercer, recalled that the European Court of Justice had set two precedents in 2007, in the cases of Viking and Laval, of restricting strikes that infringe these freedoms if they make it ‘less attractive’ to do business abroad than at home. But strikes are permissible if the action is for a ‘legitimate aim’, justified by a public interest and ‘suitable’ to achieving the aim. Govia said the proposed Southern strike was none of these: drivers’ jobs were not at risk, and the action was not proportionate. ‘We say there are less restrictive ways to achieve safety,’ Mercer said. Segal was scornful of the notion that strikes would make the British railways less attractive for a French company than operating at home; he said he ‘wouldn’t comment’ on his experience of trains across the Channel.

When questioning the union, the judge, Michael Burton, asked if lesser forms of industrial action – rather than the three days this week, followed by six days in January – might be appropriate. In his judgment he said the ‘real point’ was not safety, but that Aslef was ‘simply refusing to agree’ to the extension of driver-only operation. ‘This supports the case that industrial action is at least in part to support the RMT,’ he said, referring to the conductors’ union which has already staged multiple strikes. He also reiterated that it was Aslef’s wish to return the railways to public ownership. But he said the case had ‘not enough of a cross-border element’ to succeed on the pleaded grounds, and that the strikes’ impact on Govia’s right to freedom of establishment would be ‘indirect or uncertain’. As for the rights of passengers, ‘there will still be trains to Gatwick.’ Since there was no arguable case under the EU provisions, the judge said, there was no need to address the issues of justification and proportionality. It was the first time a union had won a case based on the Viking and Laval principle.

Aslef has long accused Govia of pursuing driver-only operation under instructions from the government. Officials find it amusing that the company is now calling on EU law when the transport secretary, Chris Grayling, is an ardent Brexiter. Aslef is one of the few unions to have supported leaving the EU, but officials say they kept quiet about that in the run-up to the case. Outside the courtroom, the union’s leader, Mick Whelan, told me he’d wanted to avoid ‘anything that would feed the right-wing xenophobia and the attacks that we’ve seen in recent months’.

But neither Govia’s failure nor Brexit itself will necessarily prevent this sort of challenge in future. It has been suggested Britain rejoins the European Free Trade Association to retain access to the single market. A ruling from the EFTA court last year, Holship, was the third case cited by Govia’s lawyers. It held that the legitimate aim of protecting workers could not justify the dispute between Norwegian dockworkers and the freight carrier Holship: it protected the interests of the unionised workers in the port, but to the detriment of Holship’s workers who weren’t in a union. The EFTA court also ruled, however, that secondary industrial action – going on strike in support of other workers, illegal under British law – is a fundamental part of the right to collective action. So when Govia suggested the drivers' strike was in sympathy with the striking RMT conductors, Aslef's QC said this argument was totally irrelevant.