Anyone passing a Westminster restaurant on a weekday morning last month might have noticed three figures enjoying an animated chat over scrambled eggs.

There is nothing particularly noteworthy about that, except that the breakfast diners were two senior teaching union officials and an education minister.

Three years ago such an informal meeting would have been highly unusual; today it is the norm.

Chris Keates, acting general secretary of the National Association of Schoolmasters Union of Women Teachers, has seen a “huge sea change” in relations between most teaching unions and the Government since 2001.

“In more than 15 years I have never worked in a climate quite so constructive and positive,” she said. “The kind of dialogue we are getting with officials, the access to information and the early consultation - it is very rare now that government announces something that is a surprise for us.”

The chief product of this quiet revolution, the workforce agreement, has had plenty of publicity, but the growing warmth between the “partners” who signed it less.

It would be unfair to describe the new relationship as a secret: its chief players often pay public tribute to their new-found co-operation. But the relationship is based on trust and relies on confidentiality: conducting disputes behind closed doors rather than publicly via the media.

How many ordinary teachers know their union leaders now spend away-days with ministers trying to resolve difficult issues? Or that Department for Education and Skills press officers and unions now tip each other off before big announcements? Or are aware just how radically the atmosphere between the leading power-brokers in English education has changed?

For the keen observer, the signs are there. Take the reaction to the announcement of the DfES’s five-year plan in July. There was much unions could embrace, but also much that one might have expected to provoke fierce opposition - and in the past had done just that.

Take for example the plan to let all schools gain foundation status. When Labour introduced foundation status to replace grant-maintained schools in 1995 the NASUWT reacted with fury.

Nigel de Gruchy, then general secretary, warned that the plan risked “making a bad situation worse” because the continued loss of funding to local authorities would jeopardise vital services.

Nine years later and the Government is encouraging a major expansion in the number of foundation schools and further reduction in the role of local authorities by making it easier for all secondaries to gain the status. Cue outrage from the NASUWT?

Well no. Faced with a vast increase in a type of school her predecessor found so unpalatable, Ms Keates, decided to concentrate on the positive.

Though there was no ringing endorsement of the policy, she gave a “warm welcome” to a pledge from Charles Clarke, the Education Secretary, that foundation status would not allow schools to opt out of teachers’ national pay and conditions.

And it is not just the NASUWT. Reaction to the five-year plan, which also contained a proposal to make it harder for experienced teachers to gain pay rises, was resoundingly positive from all teaching unions signed up to the school workforce reforms.

The blueprint made a “great deal of sense” said the National Association of Head Teachers, the Secondary Heads Association gave it a “strong welcome” and the Association of Teachers and Lecturers concluded there were “grounds for optimism”.

The one fly in the ointment was the hugely controversial goal of 200 academies by 2010. But even here, union criticism seemed a little muted though it surfaced again at this week’s TUC conference.

Mary Bousted, ATL general secretary, said there were some “crucial issues” with academies. But if Mr Clarke continued to listen they “could be resolved without his basic objectives being jeopardised”.

The origins of this new era of peace can be traced back to the talks that began on teacher workload between Government and unions in the summer of 2001.

They followed more than two decades of hostility. Teachers were never natural allies of the Tory governments of the 80s and 90s. There were high hopes relations would thaw under Labour - but it took a tough line with teachers, courting middle England with policies, deeply unpopular with the profession, such as “naming and shaming” schools.

Talks continued along the old pattern of unions marching in, saying their piece and marching out again. Hours would be spent drawing up responses in the full knowledge that ministers would ignore them.

By the spring 2000, teachers were threatening industrial action over both performance-related pay and excessive workload. And it was action in the form of the National Union of Teachers’ and NASUWT’s “cover to contract” work-to-rule in protest at teacher shortages that eventually led to the change of mood.

According to Mr de Gruchy, the Government “realised we were serious”. By the start of 2001 it had quietly dropped its teacher-bashing rhetoric and entered talks.

The DfES realised the old approach to reform of giving schools a grant and setting targets would no longer work. Future changes had to be delivered by people who believed in what they were doing.

What followed was a happy coalition of interests: unions wanted workload cut and ministers wanted to tackle teacher shortages. More use of support staff had the potential to solve both.

The “something for something” deal that emerged proved a step too far for the NUT. But in January 2003 it was signed by every other major education union in a watershed in labour relations.

It was, at last, an example of the kind of social partnership that many had hoped for under Labour. It had the backing of powerful figures such as Brendan Barber, Trades Union Congress general secretary, who played a vital role in brokering it, and has been held up as example of good practice by Downing Street.

Since then no-one has looked back. A potential hiccup in September 2003 over plans to slash the number of teachers progressing through the upper pay scale was solved by an unprecedented partnership of employers, the Government and the unions.

Within a year the partnership had quietly developed this solution to a specific issue into a way of working that could, it seemed, be applied to any problem.

Despite his own abrasive relations with government, Mr de Gruchy says social partnership was what his union always sought. “There was a long time where people just wouldn’t consider our case on its merits which I found frustrating. But under social partnership everyone gets more because whatever has been decided, everyone has ownership of it.”

Which of course does present the Government with a distinct advantage. If policies it has imposed fail then it must carry the can. But if everyone has signed up to them it is impossible for them to criticise when things go wrong.

The biggest rows have been between the signatory unions and the outcast NUT. Its former general secretary, Doug McAvoy, even accused union colleagues of being “collaborators”.

All that may be about to change with the NUT under new leadership, described by those in the know as in a “transition period” in its relations with Government.

If it does come back on board then the partnership will enter unknown territory. But for the time being, signatories are happy with the status quo. They still reserve the right to take industrial action, Ms Keates says. But she stresses: “You get more by talking than you do by threatening.”

WHAT THEY SAID THEN...

“A banana skin short of bonkers.” - Nigel de Gruchy, National Association of Schoolmasters Union of Women Teachers general secretary, reacts to a proposed new “fast-track” career structure for the the best teachers in1999.

“Teachers do deserve better pay, but the proposals to ‘modernise’ the profession are seen as ineffective, unfair and not doing enough to raise standards.” - Peter Smith, Association of Teachers and Lecturers general secretary in 1999.

“The Government need to put its weight firmly behind broadening the curriculum. This is more evidence of timidity.” - David Hart, general secretary of the National Association of Head Teachers on proposals for A-level reform in 1999.”

WHAT THEY SAY NOW...

If deploying a teacher with the support of appropriate staff with 60 pupils is the right way forward... then so be it.” - David Hart, NAHT general secretary after signing of workforce deal, January 2003.

“Because people know that we are going to have these discussions (with Government, employers and partner unions), rather than thinking it will all be imposed, it does put you in a positive frame of mind.” - Chris Keates, NASUWT acting general secretary reacting to proposals to make senior teachers coach junior colleagues if they want further upper pay scale rises, and to deny main-scale teachers annual pay rises if they are underperforming.

“If the Government is going to put millions into the workforce agreement then they are going to want some sort of quid pro quo in raising standards.” - Mary Bousted, ATL general secretary, reacts to the same proposals, made in July 2004.