Et tu, Vince? It is hard to imagine a more ignominious end than to be knifed by Vince Cable. Unless it is to be knifed accidentally by Dr Cable, simply because the deputy leader didn’t manage to hold a line on a radio interview for an entire three minutes. When Dr Cable told The World at One on Radio 4 on Monday that Sir Menzies Campbell’s leadership was “certainly under discussion” among MPs, the game was up. Coming straight after direct calls for his immediate resignation from party grandees, Sir Menzies was finished. Dr Cable stumbled; the leader fell.

The ridiculous and sudden denouement of a play that should have had a few more acts to run (ending around Christmas time seems to be the consensus) nicely illustrated the Liberal Democrats’ fundamental problem: appalling communications skills. That the deputy leader of the party was unable to keep to the formula that Sir Menzies’ leadership was not an issue says all you need to know about all they need to learn about communications.

The leader matters. It is not true that the Liberal Democrats have to accept being squeezed by David Cameron and Gordon Brown. Just because the Conservative Party no longer actively discriminates against gay people does not suddenly make it liberal. The Tories remain socially conservative. Given the two main parties’ broad agreement on tax and spend, and the funding of public services, there is plenty of economic space for the Liberal Democrats to occupy as well: liberal on economic as well as social issues, in favour of low taxes as well as gay marriage and choice in education and health.

To dismiss the “Ming thing” as straightforward ageism is to miss the point. What did it for him was that he hailed from a different political era, a postwar generation in which the media were still respectful, people generally tried to be decent and uncomplaining, and a consensus existed that there was no choice: you went along to your local hospital, and that should be a good local hospital. That isn’t enough any more, because your local hospital isn’t always good and your local school very often isn’t, and people do complain, a lot.

One of the frontbench modernisers, David Laws, the spokesman for children, schools and families, addressed the problem in his conference speech this year: “Our aim, of course, must be a good local school in every single neighbourhood. But that is an excellent aspiration, it is not a policy. The challenge is how you get high-quality local schools in every area.” Some of the younger (and more centre-right) Liberal Democrats detected a lack of enthusiasm in Sir Menzies for the “choice” agenda to put power into the hands of people to choose and effect change for themselves.

Then there was the communications vacuum. Sir Menzies either couldn’t or wouldn’t do it: no soundbites, no clever tricks, no clear message, no narrative. Politicians have to have a message and a narrative these days; they die in the many airwaves if they don’t. Charles Kennedy created a narrative, but it was all about him, not policy. Sir Menzies created policy, but no narrative. You need both.

There is no point complaining about the 24-hour media and their voracious appetite for soundbites; they just are, and people watch them and they listen to them, and a party leader has to be utterly comfortable with that. Sir Menzies wasn’t. That is why, for instance, he was sucked into the maw of what he thought was a perfectly reasonable 24-hour gap to consider whether Liberal Democrats should participate in Gordon Brown’s Government “of all the talents”, Twenty-four hours is a vast gap in media life; and Sir Menzies fell into it when somebody briefed the plan to The Guardian before he had a chance to turn it down. That was hopeless.

When I interviewed Sir Menzies with my colleague Helen Rumbelow last month, a memo sat on the small table between us. Ming had made no attempt to hide it. “You should assume,” an unnamed adviser wrote, “that Alice and Helen are coming into the room expecting to find someone who is old, tired and lacking in the vision that leadership requires. For the interview you need to bear this in mind by being positive, purposeful and by being relaxed when they ask personal questions.” Having broken the old-fashioned rules of decency to which I knew he would have adhered, and published the memo as part of the interview, I was slightly alarmed to see Ming bear down upon me at the Liberal Democrat conference the following week. He came up and kissed me, commenting that it was “a very fair piece”. Nice, you see.

Too nice. Being “fair” is something Sir Menzies minded about a lot, and it showed. In his interventions in the Commons, in the strings of e-mails that tumbled out of his office, his lack of any cutthroat instinct was obvious. And, like it or not, fair and nice doesn’t win.

Which makes me wonder about Nick Clegg. Mr Clegg, whom Sir Menzies is assumed to be backing to succeed him, is personable, bright, a young family man. His rise has been swift and easy, and his lack of experience was apparent when he stumbled last month into an honest admission that he might one day go for the leadership, if there was a vacancy, and then was apparently surprised at the “Clegg pitches for Ming’s job” headlines which followed. Mr Clegg is, or seems to be, terribly nice and quite human.

Chris Huhne, on the other hand, is mesmerisingly cold and charmless, almost robotic. If Mr Huhne were to wield a knife (and perhaps he did), it would not be by accident. Yon Chris has a lean and hungry look. Such men are dangerous. Mr Kennedy was nice. Sir Menzies was nice. Nasty may be what this party needs.

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