It might be one of the biggest issues facing the world but it's been the lost issue of the 2005 general election in Britain. In the clash of political argument and invective between the parties, the environment has hardly figured.

It might be one of the biggest issues facing the world but it's been the lost issue of the 2005 general election in Britain. In the clash of political argument and invective between the parties, the environment has hardly figured.

However, analysis of the three main manifestos, plus that of the Greens, indicates why.

It is almost certainly because the Conservatives, under the tutelage of the Australian political strategist, Lynton Crosby, have ruthlessly rejected all but half a dozen issues to campaign on as vote-getters - and the environment is not among them.

It is generally agreed that, in the weeks leading up to the official campaign, the Tories were setting the agenda and Labour was responding, especially on issues such as immigration. The pattern has been Tory attack, Labour defence - so, in effect, the Conservatives have been choosing the battleground.

Just how that battleground was being defined by the party was made crystal clear last week by publication of the Tory manifesto, a document fascinating for its conciseness and tight focus. It is only 7,200 words long, compared, for example, to the 16,000 words of the Liberal Democrat programme and even more for Labour's. The bare, photo-less cover simply lists six issues: more police, cleaner hospitals, lower taxes, school discipline, controlled immigration and accountability.

These, Mr Crosby clearly believes, are what floating voters care enough about to consider switching back to the blue rosette. As key issues, everything else - the fate of the planet included - is binned. Never mind that Mr Howard was the environment secretary who represented Britain at the Earth Summit in Rio de Janeiro in 1992. You can almost hear Lynton Crosby's dismissal: No votes in that, Michael. The environment features only as a subsection of a subsection in the chapter on Accountability.

While the other parties all make much of the environment, with surprisingly, the Liberal Democrats going even further than the Greens, the scale and sheer ruthlessness of the excision of it from the Tory manifesto appears the more remarkable the closer one looks.

Let's have a little linguistic analysis. Look at the use of the words "environment", "environmental" or "environmentally".

In the Liberal Democrat manifesto, the words are used a total of 62 times; in the Green party document the words occur 34 times; and in Labour's a total of 30 times.

In the Conservative manifesto, if one does not count the sentence, "classrooms need to be disciplined environments where children can learn", the word "environment" is used a mere three times (twice in headlines), the word "environmentally" is used once, and the word "environmental" not at all, for a grand total of four references - less than one fifteenth of the number of mentions the Liberal Democrats give.

This is not to say, of course, that the Tories do not have a range of thought-through policies on environmental questions. They do, and they can be found if you dig into the party's website. But in the showcase document they are not the policies that matter, in the battleground they are not the policies chosen to be fought over - and so they have been off the agenda.