The National Education Union (NEU) has been created from a merger of the National Union of Teachers (NUT) and the Association of Teachers and Lecturers (ATL), with a membership of 450,000 members — making it the fourth largest affiliate to the TUC.

The new union is a product of a decades-long campaign to promote professional unity among teachers.

NUT leader Kevin Courtney, who becomes the NEU’s joint general secretary, said: “This is a pivotal moment in education and members need a united voice to speak loudly and authoritatively on the issues that matter.

“The school funding crisis, high workload, threats to pay and conditions and the dire problems in recruitment and retention — all are burning issues within the profession, and the National Education Union will be a formidable presence at the forefront of those debates.”

Members formerly in the ATL or NUT will continue to be supported by their union’s current staff and lay officials until January 2019.

Unlike the NUT, the new union will be open to all education workers, including support staff — who have already been represented by the ATL.

The NEU’s other joint leader, former ATL chief Mary Bousted, said: “The National Education Union is a game-changer combining ATL’s diversity of members, excellent training and policy expertise with the NUT’s campaigning and lobbying skills and well-established, effective local activity.

“It is a union ready to meet the current challenges, particularly in funding and in workload, and to speak with authority as the voice of the majority of teachers and other education professionals.”

As many as eight education unions still remain, including the substantial NASUWT. But the NEU’s leaders hope to persuade other organisations to merge into the new bloc at a later date.

Hank Roberts, whose Unify campaign has led the charge for professional unity, said: “I can hardly express my delight. This is a game changer and will make it much harder for this government to continue its divide-and-rule tactics in taking forward its plans to privatise the management of state education to open it up to be run for profit.

“The big question, though, remains: will this be the end of a process or a new beginning?

It must be a new beginning. We are not finished by half. Our task now is no less to unite the whole of education into one union. It would be a million strong.”

“We have nothing to lose and a whole world to gain.”