“Why did the chicken cross the road? To avoid the TV debates.”

For that rib-tickler we have Ed Miliband to thank, performing at a weekend comedy festival (the Fabian Society annual conference). It wasn’t as funny as his bacon sandwich routine, but well done anyway.

Or maybe not. Tactically, he’d be better off keeping quiet about the issue. By hiding behind his friends at the BBC, he can make this look like a row between the Conservatives and the broadcasters.

This is how George Eaton at the New Statesman characterises the issue:

“In threatening not to participate in the TV debates unless the Greens are included, David Cameron has called the broadcasters’ bluff. His hope is that they will now either extend their invitation to Natalie Bennett’s party, or cancel them altogether. The former would ensure the presence of a rival left-wing party to Labour and the Lib Dems (compensating for the Tories’ Ukip problem), the latter would allow him to avoid an event that he believes he has most to lose from.”

Of course, Ed Miliband has an equally cynical interest in keeping the Greens out of the debate. But, luckily for him, it is the broadcasters who have made the decision – allowing Labour to stay out of the row. If this is just about the Conservatives and the media, it might look as though the former are trying to strong-arm the latter:

[Cameron’s] self-interested stance is a test for the broadcasters… I, like others (including Labour’s Sadiq Khan), believe that the Greens should be included in at least one of the debates. But to capitulate now would undermine the media’s independence. The Greens should be included or excluded on their own merits, not at the say-so of Cameron.”

Fair enough – but it shouldn’t be at the say-so of the broadcasters either. While the BBC and the other networks have the privilege of hosting the debates, they should not own them in the way that they own their regular programmes.

The media already have a huge degree of influence over the political process – so to give the broadcasters the power to choose who gets a platform in the single most important event of the election campaign is to grant excessive power to a narrow elite. This is especially true at a time when the tectonic plates of the party system are shifting.

The broadcasters have a pretty poor record in recognising game-changes in party support. For instance, in the 1999 European elections the BBC failed to spot the emergence of UKIP as a significant force – instead granting the oxygen of publicity to an obscure outfit called the Pro-Euro Conservative Party. More recently, the rise of the SNP has visibly wrong-footed the corporation. And, crucially, the current surge in Green Party support has happened despite the media’s long-standing lack of interest.

So, in a national forum like the TV debates, why should the flawed editorial judgments of a few broadcasters be allowed to trump public opinion?

In last week’s diary for ConservativeHome, Iain Dale made a sensible suggestion:

“It’s actually the broadcasters’ own fault. They should have set up a formal Debates Commission after the election, which could have solved all these problems independently of the political parties and broadcasters. One must be set up later this year so that we don’t have these squabbles next time around.”

On what basis should such a body make its rulings? I would propose the following three principles:

Firstly, to recognise that there are significant differences in the English, Scottish, Welsh and Northern Irish party systems and that, consequently, each nation should have its own TV debate.

Secondly, that the criteria for inclusion in the debates must not embed the status quo – i.e. they should reflect the relevance of each party to the forthcoming general election not the previous one. This should be judged across a number of criteria, including opinion poll ratings, party membership numbers and performance in recent by-elections, European elections and local elections.

Thirdly, no party should be excluded from the debates unless there is a clear gap across most of the relevance criteria between it and all of the parties that are included.

In England, applying these principles would produce a balanced five-way debate including the Greens – as opposed to the current Labour-enabling stitch-up that Cameron is right to reject.