Teaching unions regularly employ staff with a facility for detailed policy analysis. Similarly, their ranks are filled with empathetic listeners who are prepared to discuss members’ problems at length.

But Ian Foster, assistant secretary of the National Association of Head Teachers (NAHT), had a far rarer skill: he was able to combine extensive knowledge of government policy with a natural ability to put troubled union members at their ease.

Ian Foster was born in Oxford in 1946. His father’s military career took the family to Tobruk, in Libya, where Ian attended an army school. Later, he was sent to Magdalen College School in Oxford.

On graduation from Durham University, he took up a teaching job at a primary school in Battersea, south London. Within three years, he had been appointed deputy head of a Berkshire primary. He was 28 years old.

His rise to school leadership was similarly rapid: by 1981, he was head of Shefford School in Berkshire. That same year, he joined the NAHT. From the start, he was an enthusiastic member: from 1985 onwards, he did not miss a single conference.

The desire to help others that had motivated him to enter teaching in the first place now led to increased involvement in the union. He held three headships in total, the last at Leonminster Junior School in Herefordshire. And the longer he was a headteacher, the more he felt that he possessed experience and knowledge worth imparting to other union members.

And so, in the 1990s he became branch secretary for the NAHT in Herefordshire, complemented by a year as Herefordshire branch president in 1994. In 2000, he was elected president for the West Midlands region.

Such roles were inherently suited to him: he had a natural charisma that made him easy, comfortable company. On catching sight of Mr Foster in a room, colleagues inevitably - and immediately - sought him out for conversation.

But as well as being entertaining company, he was also a natural listener. When troubled members approached him for advice, he would rarely offer it. Instead, he allowed the headteacher to talk, asking occasional pertinent questions. Often, this was exactly what was needed: he subtly directed heads to their own conclusions.

But his interest in union work was political as well as personal. In 2005, he was appointed vice-chair of the NAHT’s primary committee. Here, he was responsible for determining primary-related policies, vital to the union’s largely primary membership. It was he, for example, who wrote the union’s response to Sir Jim Rose’s recent review of the primary curriculum.

He thrived on detail: few knew more about primary policy than he did. Whenever Mick Brookes, current general secretary, wanted to test the wisdom of a primary-related idea, he would approach Mr Foster. Consensus was that if Ian Foster approved something, it was likely to be OK.

Union work left Mr Foster little free time. But he made a point of going hill-walking regularly. He also enjoyed cooking: his rabbit stew was renowned among colleagues. And he was a dedicated supporter of Oxford United FC: “Well, someone has to be,” he said.

In 2006, he left Leominster to take up a full-time post as assistant secretary of the NAHT. In this role, he became what colleagues described as the “engine room” of anti-Sats campaign work. Working together with the NUT, he helped to develop an anti-testing campaign, ploughing through policy documents and drafting press releases.

Inevitably, he missed the day-to-day interactions of school life. Nostalgia tended to strike when he was invited to a school play or sports day.

But he was also convinced that it was time to move on: he felt that it would be wrong not to share the wisdom he had gained with less experienced colleagues.

An unsuccessful marriage had produced two children, Rachel and Richard. Richard had moved to Australia and was raising a family there. Mr Foster was preparing to spend the Christmas holiday with him (“Off to Australia. Yippee!” he had written in Christmas cards) when his car ran into an articulated lorry on December 4. He did not regain consciousness and died on Christmas Day.

Ian Foster, 63, is survived by Rachel and Richard, and by his grandchildren.