It really is profoundly depressing to realise that the only reason the broadcasters were ever going to agree to do the decent thing over the leaders' debates was that they needed a tactic to try to cajole David Cameron into taking part. So much for that innate sense of "British fair play". But it doesn't really matter a damn how we got here - the point is that a Rubicon has now been crossed, because Scotland has heard the broadcasters accept the principle of SNP involvement in the main debates, which in practice will make any back-pedalling almost impossible. (In any case, if there were to be any foolish attempt at a retreat, I would imagine the prospects for a successful SNP legal challenge have just been considerably enhanced.) There are really now only two possibilities - a) Nicola Sturgeon will have some kind of place in the main debates, or b) there won't be debates at all. Either is absolutely fine as far as I'm concerned, because the SNP won't be disadvantaged. Basic fairness was all we ever wanted - nothing more. Why the London establishment initially reacted to that modest request as if we were demanding golden elephants will always remain something of a mystery.
There is of course still a wrinkle attached, with the proposal being that only two of the three debates will be inclusive. The other is supposed to be a Cameron v Miliband head-to-head. That's thoroughly reprehensible, but it probably won't be too damaging. The main battle in a Westminster election is simply to ensure that voters don't forget that the SNP exist and are one of the choices. Inclusion in two of the debates should be sufficient to achieve that, and the 'Prime Ministerial' debate may simply reinforce in people's minds how much more inspiring political discourse becomes when the choice is widened.
If the debates do go ahead as proposed, the big losers will of course be Jim Murphy and Jim Murphy's Status. It won't be Jackanory Jim who'll be seen to be Nicola Sturgeon's Labour opponent, but Ed Miliband. And that's just as it should be.