The BBC's TC1 Television Studio, site of the 2010 election debate. Image: Nick Garrod / Flickr

The broadcasters - ITV, the BBC, Channel 4 and Sky News - started with three proposed debates: a 2/3/4 format, in which there would have been Cameron v Miliband, Cameron v Miliband v Clegg, and Cameron v Miliband v Clegg v Farage, all to take place between 2 and 30 April.

Everyone except Cameron said yes to that (the Greens, Plaid Cymru, the SNP and the Democratic Unionists seemed resigned to their non-appearance).

Cameron’s first position was that he did not want to debate inside the period from the dissolution of Parliament (scheduled for 2 April) and polling day (7 May), that he would only do one debate (implicitly the multi-leader one, as his advisors confirmed his unwillingness to go head-to-head with Miliband), and that he could not understand the exclusion of the Green Party, given that it was polling at the same level as the LibDems.

Somewhat surprisingly, the broadcasters then dumped 2/3/4 in favour of 2/7/7 (expanding the 4-way, twice, to include not just the Greens but also the SNP and Plaid Cymru), all still within Cameron’s excluded period. But if this flip was designed to induce Cameron to commit to more than one debate, it failed pretty quickly (whilst infuriating UKIP – who were edged out of a promised 4-way – and puzzling the DUP – why should the SNP and PC be there, but not us?).

Cameron declined everything other than one of the 7-ways, and asked for it to be moved forward to March. All the other parties criticised his “intransigence”, even Clegg (who had now lost a promised 3-way debate as originally proposed). The newly-invited parties churlishly ignored the fact that only Cameron’s “intransigence” had delivered their participation, and joined the chorus of condemnation. Two Tory peers - Lords Grade and Dobbs- wrote newspaper articles criticising the broadcasters and the BBC in particular for briefing their intention of replacing Cameron with an empty chair if he declined the package.

In my last post I predicted that Cameron would succeed in avoiding a head-to-head with Miliband, and that the strongest likelihood was for there to be just two debates. The final version of the broadcaster deal confirms that expectation: indeed, only one of the debates will include Cameron, and although it will be broadcast by ITV on 2 April after all - and not in March as he had insisted - this is a very minor concession on his part.

A second debate will have just five participants but without Cameron or Clegg. The briefings from various interested parties as to how this curious format was devised are not compatible with each other. The notion that Cameron 'forced' Clegg not to participate (on the grounds that he could not be allowed to 'represent' the coalition government) does not ring true: Clegg could surely have ignored such a protest. That two non-debate televised events have been added to the package perhaps provides a clue: Clegg will now be one of three leaders interviewed separately before the same BBC Question Time audience (and then subject to questioning by the audience), a week before polling day, so restoring the appearance of a 3-way (and thoroughly annoying Farage, as the 4-way has not been restored).

This allows the second actual debate to be billed as 'the opposition parties', so avoiding the embarrassment of invoking an 'empty chair' for the Prime Minister. This was something the BBC had been urged to do as a way of “standing up” to Cameron’s refusals, but which carried heavy risk if the Tories then went on to win the election. Why Miliband’s advisors would have allowed him to appear in such a format (the “night of the nobodies”, as the Tories have dubbed it) is a mystery: perhaps his rhetoric about “anytime, anywhere” trapped him. This event seems unlikely to win much audience for the BBC on 16 April.

The whole sequence will kick off this Thursday with a 2-way version of the 3-way format which had been scheduled for 30 April: Miliband and Cameron will be separately interviewed (who goes first has yet to be revealed). Channel 4 and Sky News will both broadcast this live. So Cameron has succeeded in pulling this encounter forward to before the five weeks of the campaign, and in avoiding a direct debate, whilst agreeing to two TV events over and above the one he originally agreed to do. If this were a tennis match, it would be scored as a comfortable straight sets win for Cameron.

What of the BBC? What might have turned into an unpleasant confrontation with Downing Street has been successfully finessed, with only light bruising on each side. Even so, the BBC looks much more vulnerable to a Conservative victory on 7 May than a Labour one. Although Labour has supported the move towards decriminalisation of the licence fee, it would be much less likely to overturn the recent Lords amendment to the Deregulation Bill (whereby such decriminalisation was postponed to 2017) than would the Tories.

The continuing success of the BBC in terms of audience share and share of news consumption, despite the seemingly punitive licence fee settlement of October 2010, makes any hope of an increase in the licence fee after the election seem remote. Tony Hall’s call for the iPlayer to be covered by the licence fee is bound to run into the objection that access to the iPlayer is easy to monetize, Netflix-style. Closing BBC3 – if the BBC Trust gives its approval – will save little in the way of cash, and impress few politicians as a demonstration of financial pressures (especially as it will be replaced by a +1 channel for BBC1, which will generate audience share but not a single new programme).

Yet the march of changing audience behaviour is inexorable. Last year, for the first time, the number of TV homes (and therefore homes liable to pay the licence fee) declined by several hundred thousand. There are now nearly a million homes which have broadband access to video content, but do not have a conventional television. Netflix subscribers are rapidly increasing in number (well over 3 million already), and video downloads of the iPlayer on to tablets and smart phones are growing exponentially. Last year, nearly half all video downloads from the iPlayer were to mobile devices – next year, the proportion will be higher still. All the increase in iPlayer downloads is coming from mobile. Only a charging mechanism for the iPlayer can prevent the BBC’s revenue stream being cannibalised by the viewing connection most popular with the public, at the expense of licensed TVs.

The kinds of long-term replacements for the licence fee canvassed by the recent House of Commons report will not arrive in time – if at all – to save the BBC for the first time in its history from actually suffering a revenue decline. There will be little time between the election and the expiry of the present Charter for the BBC to refine a survival plan and sell it to Whitehall. This year will be crucial.