Who is going to get the education vote at the general election?

It is an important constituency. It is also a big one. As the Americans say: "Just do the math."

There are some 500,000 teachers, 300,000 school governors and thousands more who work in local education authorities, teacher training and school inspection and advisory services.

Their influence may not stop there. Teachers, especially head teachers, can have significant influence on parents' views.

A communication from a head teacher about the budget or class sizes at your own child's school is likely to have more impact on parents than any politician's claims.

With over seven million children in schools, that's a lot of parents.

'Unpredictable'

The teachers' vote is also more unpredictable than many might expect. Opinion polls suggest that just over half of teachers supported the Conservatives in 1979.

Although this number appears to have dropped at each successive election, as late as 1983 the Tories still enjoyed the support of more teachers than any other party.

According to ICM polls for the National Union of Teachers, the big shift against the Conservatives came in 1987 when 46% of teachers said they would support the Liberal Democrat Alliance, with 28% supporting Labour and 24% the Conservatives.

More recent polls, for the Times Educational Supplement, suggested that teachers' support swung dramatically to Labour in 1997. Although it may have slipped back a little since then, the TES's most recent poll, in January this year, suggested that just over half of teachers would still support Labour.

The National Association of Schoolmasters Union of Women Teachers said on Monday that 53% of its members voted Labour in 1997, but only 42% would do so next time.

Economic considerations

Naturally, like the rest of the electorate, teachers probably do not make their voting choice on education issues alone.

Most political analysts say that, whatever voters may say to pollsters' questions about which issues matter most to them, it is the economic impact on their pocket which determines most votes.

Nevertheless, winning the support of the teaching profession, especially head teachers, is important to politicians.

That is why last weekend's head teachers' conference was graced with visits from not only the education secretary but also, unusually, two party leaders.

Salesman's pitch

Like travelling salesmen, education secretary David Blunkett, Tory leader William Hague, and Liberal Democrat leader Charles Kennedy paraded their wares for the Secondary Heads Association. It was a fascinating insight into how the parties intend to appeal for the education vote.

The education secretary started with a disadvantage as head teachers are still fuming over Downing Street's promise to bring about the end of the "bog standard comprehensive".

Rarely has an off-the-cuff remark by a Downing Street spokesman aroused such ire. Not surprisingly Mr Blunkett was asked to repudiate the phrase.

He cleverly avoided doing so by deflecting the question from bog standard schools to school "bogs" (or lavatories to the more refined). No apology or repudiation, but the lack of endorsement for the phrase spoke volumes.

Indeed, despite their frustration over the denigration of comprehensives and over school spending, head teachers warmed to Mr Blunkett.

Fond 'farewell'

Since it is now widely believed he will not be the education secretary after the election - whatever the outcome - he was given the sort of reception normally provided to a popular, but slightly feared, colleague about to leave for promotion elsewhere.

What was clear from his speech, though, was that Labour will rest its election appeal on what it has done in the primary sector and what it now hopes to do for secondary schools. In short, his speech was an unashamed plea for more time to finish work that has only just begun.

The reception accorded to the two party leaders was rather different. Each was under 40 (although Mr Hague passed that landmark the very next day) which made them younger than most head teachers in the hall.

But whereas Mr Kennedy was received like the bright former head boy back for prize day, Mr Hague was treated as a ferociously bright, but slightly truculent sixth former who had had the temerity to challenge the head's authority.

'Bashing socialists'

Mr Hague did have the advantage of being introduced by his former politics teacher (now a head teacher).

This started off proceedings with a warm, nostalgic glow as he recalled that while other boys' hobbies included soccer and stamp collecting, young William's stated hobby had been "bashing socialists".

In fact, Mr Hague surprised the head teachers by falling on the sword of the Tory record before anyone could stab him with it.

Past Conservative governments, he admitted, had been guilty of excessive intervention in schools.

It was a clever way of getting across his main appeal to the education vote - in short, the Conservatives will set schools free to set their own policy.

Kennedy's warm reception

Mr Kennedy's reception was probably the warmest of all.

Adopting the low-key, casual speaking style which seems to suit him best, he was cheered on as he promised higher school spending and smaller class sizes.

But it was noticeable that while both Mr Blunkett and Mr Hague were given challenging questions at the end, no-one seemed to have the appetite to take on Mr Kennedy.

Was it because they agreed with everything he said or because they think it is unlikely ever to be put into practice?

With uncertainty over the election date, the parties are keeping their powder dry for the campaign proper. That is why none of them came out with any surprise announcements.

But, with the teacher unions' traditional Easter conference season about to start, there will be many more appeals for the education vote.