It isn’t very difficult to understand why David Cameron has insisted that he won’t be involved in the planned TV debates before the General election. One thing it is not about is a genuine commitment to the environment. What it IS is a pure political calculation, that makes a lot of sense.

What I can assure you this is NOT about is Cameron hugging a husky, promoting wind farms (despite the profit his wife’s family makes from them) nor the honourable idea of having a woman up on the stage at a debate for the first time.

Under our election system of First Past the Post, all a candidate has to do to win a seat is to achieve a ‘simple plurality’. This means that they just have to get more votes than the party with the second highest number of votes. In an extreme example this means that in a constituency where Labour gets 15,000 votes, Conservatives get 14,999 and UKIP gets 14,998 votes, Labour wins, even though the electorate is on the majority right-leaning.

I say it is an extreme situation, but it is serious for Cameron, because many Conservative voters are considering voting for UKIP, and earlier today OfCOM, who are regulating media coverage of the election, said they were considering designating UKIP a ‘major party’. This would mean that they get as much airtime as the other three main parties. They would get a clip in every broadcast about the election, they would be invited to have their candidate featured in every broadcast from a constituency, and they will be allowed the same number of party political broadcasts as the others.

OfCOM are NOT considering this status for the Green Party, and these two put together as far as Cameron sees it (rightly), could be disastrous for his Party’s election chances. The more voters leak to UKIP on the right, the less chance Conservatives have of winning marginal seats against Labour. If, however, he can get the Greens in the debates at least, and I wouldn’t be surprised if he pushes for other forms of exposure for them, then those left-leaning Labour voters who are uncomfortable with the current Labour position on austerity for instance may be more likely to go to the Green Party, making it more likely that the Conservatives can win marginal constituencies where there is a decent Green presence to take enough Labour voters away. Where there is a Lib Dem/Conservative marginal, those left-leaning Lib Dems voters who feel betrayed by the Party’s involvement in the Coalition’s austerity programme might also slip to the Greens.

Don’t take it from me though, take it from Cameron himself…whose private view, it was reported was “if we, the Conservatives, are to get hurt by the people to our right, UKIP, then Labour and the Liberal Democrats should get hurt by people to their left, the Green Party”.