Let’s start off with the sentence you’d expect me to write: Vince Cable won last night’s Channel 4 Ask the Chancellors debate. There, I’ve said it.

Of course, it’s not just me saying it. It’s also The Guardian (“Vince Cable draws first blood”), the Telegraph (both Ben Brogan and Janet Daley), New Statesman (“Cable triumphs”), Channel 4 (Cable “man of the match”), Financial Times, Spectator and Independent (“Cable comes out on top”). And I’ve probably missed a few others.

Vince Cable

Vince started off with two big advantages, and two big disadvantages.

First, the advantages: he understands the economy, and how to convey a message to voters, like no other British politician. He looks the part – a very reasonable, persuasive bank manager – but he can also twist the knife with a turn of phrase that leaves its victim sprawling and the audience smiling.

The second advantage was a much simpler one: he was stood in the middle of the set, and – as a tall man – was able to dominate the proceedings, by turns interrogator, at other times umpire. But always in control.

Now to the disadvantages.

First, the expectations. Poll after poll over the last few weeks shown Vince to be the “People’s Choice” as Chancellor, the latest being a poll last night specially commissioned for Channel 4‘s debate. As a result, the pressure on Vince to take the debate by storm was immense: a low-key competent performance just wasn’t an option for him. (I’ll come back to that in a moment, when discussing George Osborne).

Secondly, a Vince win was pretty much factored into everyone’s expectations. Which means that now he’s generally accepted to have won the debate, “all” he’s done is meet folks’ expectations. It can be a tough gig being the nation’s favourite.

George Osborne

But what of George Osborne?

You can hear the collective sigh of relief from the right-wing today that their boy, although clearly the most nervous, didn’t goof too badly. There was only one clanger, when the Tory shadow chancellor attempted to big-up his credentials by declaring, “I’ve been shadow chancellor for five years so I’ve been watching people do the job.” We’ve all been in interviews where one of the candidates tries to stretch their thin CV to cover the gaps in their experience: it’s always excruciating to watch.

Other than that, Mr Osborne was not too bad. It was a low-key, competent performance (to coin a phrase), and it’s come to something when the Tories can believe that to be good enough for the man who might in a matter of weeks be running the British economy.

It reminds me of the line from The West Wing, when White House press officer CJ Cregg worries that the Republican candidate could be seen to win the debate because of the low expectations of him: “If the whole thing is, he can’t tie his shoelaces and it turns out he can, then that is the ball game.”

Well, George Osborne can tie his own shoelaces. But the real problem for the Tories – which last night’s debate laid bare – is not that Mr Osborne is incompetent. He isn’t. The problem is that everyone can see that he just isn’t quite ready yet: he’s a bit callow, a bit out-of-his-depth, a bit rabbit-in-headlights. And the problem that’s even bigger than that one is that the economy should really be the Tories strongest card at this election – and it isn’t.

What should really worry the Tories about Mr Osborne’s performance is its opportunity cost. Last night, the best that could be said about the Tory shadow chancellor was that he didn’t lose his party any votes. He just about pulled it off.

But imagine, just imagine, if instead of George Osborne the Tories had fielded Ken Clarke, the nation’s second favourite politician to be Chancellor. Suddenly Vince would have had an equal. And that would have changed the dynamics of the debate quite dramatically. But David Cameron stuck by his friend, and in doing so has cost his party dear.

Alistair Darling

Alastair Darling was also on the stage. He did alright.

Last night’s winner:

Channel 4 (for winning back some much-needed news-credibility having been comprehensively out-manouevred by Sky News over the leaders’ debates) and Krishnan Guru-Murthy for excellent chairing. Oh, and Vince, obvs.

Last night’s (sore) loser:

Tim Montgomerie for – alone among commentators – scoring Vince as the debate loser, and for alleging without evidence that Channel 4 had packed the audience with Lib Dems.