A “game changing” new education superunion would only be able to launch national industrial action if the issue was “absolutely critical”, its co-leader has said.

Mary Bousted, the joint general secretary of the National Education Union, said the organisation would also have to “mobilise effectively” to get over a strike-busting trade union law.

The comments came in an exclusive first interview with the new union’s joint leaders, Ms Bousted and Kevin Courtney.

The ATL and the NUT teaching unions officially amalgamated today to form the NEU. With a membership of over 450,000 people, it is the largest education union in Europe, the fourth largest union in the TUC, and encompasses a majority of all teachers.

“Kevin and I are really ambitious and we’ve both said that the NEU will be a game-changer,” Ms Bousted told Tes.

However, questions remain over whether the new union will be prevented from taking national industrial action because of legislation introduced by the government last year. Under the Trade Union Act 2016, to take industrial action public sector unions must pass a “double threshold”, with 50 per cent of all eligible members returning their ballot papers and 40 per cent of all members voting ‘yes’ to the action.

Asked whether the NEU would be able to surmount the double threshold, Ms Bousted said: “There is no doubt that the Tory anti-trade union law has improperly restricted the right of public sector workers to take industrial action. Our response to that is that if you put the threshold that high, we will work to organise.”

“I’m certainly not saying there won’t ever be national industrial action again. The issue would have to be absolutely critical and we would have to mobilise effectively.”

She said it was likely that the nature of industrial action would change, with an increase in “school-by-school action” where it is easier to achieve the thresholds.

Mr Courtney said the Trade Union Act was “extremely undemocratic”.

“The Brexit referendum didn’t meet the thresholds - it didn’t get 40 per cent of eligible voters in favour of Leave,” he said.

“So you can leave an institution you’ve been part of for 50 years but we can’t call a one-day strike that our members don’t have to take part in on the basis of the same vote.”

Mr Courtney also said the NEU would be able to meet the thresholds and take industrial action at a multi-academy trust level if necessary.

“There’s absolutely no reason we wouldn’t do that in a MAT where the issue was a trust-wide issue,” he said.

However, Mr Courtney said he believed it was still “possible to reach those thresholds at a national level”, pointing out that ATL and NUT reached them in 1992 in a Sats ballot.

The NEU leaders identified the “funding crisis” and “overwhelming” workload as key priorities for the new union.

Ms Bousted said the unions’ school cuts campaign during the general election showed that providing information to parents could be a more effective way of getting the government to change course on funding than industrial action.

“It’s not industrial action, it’s information that persuaded the government to put the extra £1.3 billion in,” she said.

“My view is that if you’re looking at education funding, the power of information, campaigning and the moral case you can make is extremely powerful. I think for funding that’s probably a more effective route.”

This is an edited article from the 1 September edition of Tes. Subscribers can read the full article here. This week’s Tes magazine is available in all good newsagents. To download the digital edition, Android users can click here and iOS users can click here