With the recent damaging splits over the school workforce agreement and the choice of his successor still looming large, it may not be quite the send-off the smooth-talking 65-year-old had hoped for.

But even those grassroots members who have found themselves at odds with his tactics in recent months pay tribute to the enormous job he has done in raising the association’s profile since 1978.

Back then Mr Hart remembers conference as an old-fashioned, deferential affair.

He said: “The national anthem used to be played, the women on the top table had to wear hats and everybody had to stand when the top table walked in.

Conference today is much more business-like and the flavour of debate has changed dramatically.”

In the late 1970s the debate over the abolition of corporal punishment was still raging and midday supervision of school meals was exercising many heads’ minds.

A bust-up between the president and an education correspondent at conference in 1974 had prompted a walkout by journalists and one of Mr Hart’s first tasks was a “pretty quick repair job” on media relations, aided by a consultant.

It is an area he has excelled in since. His conference highlights include Tony Blair’s two visits as Prime Minister in 1999 and 2004, and the disastrous speech given by John Patten, Conservative education secretary, in the early 1990s.

“Members gave him a rough ride. I think that reception finished him off as secretary of state.”

He sees conference as an important shop window for the association. But as Mr Hart prepares to say goodbye to 70-hour working weeks and spend more time with his wife Frankie at home in Cumbria, he has controversial advice on its future.

“NAHT needs to get to the position where national council can be given the power to make policy between national conferences because in our world things move very quickly.”