Last week David Cameron gave a straight answer to a straight question. That’s something most of us are desperate for politicians to do more often. We crave it, like children starved of love – we get driven mad by its perverse absence. Just say what you think, we implore, just answer the question! Stop evading our inquiries and trying to work things round to some prearranged spin-doctor-approved set of phrases and priorities.

Please, just for a second, be like a normal human and talk to us, tell us what you think, tell us what you’re going to do! This is what we inwardly beg as a politician is asked something on TV or radio, in the moment before the inevitable “I think the real issue here…”, or, “The more important question we need to ask is…”, or, “Hang on ’cos, you know, we need to be clear about this…” crushes our hope once again.

So when a journalist asked the question “Would you go for a third term?” and the prime minister simply said “No”, you’d think that was worth a standing ovation. It’s so exactly what we slag off and hate politicians for not doing. The smart money was on a “I don’t think now’s the time to be thinking that far ahead”, or, “That’s an issue that I’ll discuss with colleagues as and when the time comes”, or even a disingenuous, “Gosh, I haven’t really given that a lot of thought”. But Cameron did what his lot stereotypically never do and answered the bloody question. In two letters. Bravo.

But it did not go down at all well. A Liberal Democrat spokesman declared it “incredibly presumptuous… to be worrying about a third term as prime minister weeks before the general election”, while Douglas Alexander, Labour’s election strategy chief, said “It is typically arrogant of David Cameron to presume a third Tory term in 2020 before the British public have been given the chance to have their say in this election. In the UK it is for the British people and not the prime minister to decide who stays in power.”

I find both remarks infuriating. At least the Lib Dem had the grace to remain anonymous, but you’d have to hope Alexander, a privy counsellor and former cabinet minister, is now weeping over his statement while repeatedly wailing “What have I become?!” He absolutely knows that Cameron isn’t presuming anything at all. The question was “Would you go for a third term?” – that’s “go for” as in “put yourself forward for” or “apply for”. The exchange is quite clearly based on the premise that, for someone to be prime minister, it requires the electorate’s consent. But it also requires the consent of that someone, which is what the interviewer was inquiring about. Obviously. As Alexander fully understands.

Yet he has chosen not only to ignore that fact, but to imply Cameron doesn’t even accept that “the British people… decide who stays in power”. So Cameron isn’t just arrogant, he’s an aspirant usurper. He’s flying in the face of democracy – simply by answering the question “Would you go for a third term?” with the word “No”. Though I doubt the word “Yes” would have appeased Alexander either. That, surely, would have seemed even more arrogant. So basically, neither answer to the question would satisfy Douglas Alexander. What he’s saying, we must conclude, is that Cameron shouldn’t have answered the question at all. He should have evaded it. That, the Labour strategist has chosen to contend, would have been the proper course for a prime minister: to avoid answering perfectly reasonable questions.

I can’t help wondering if it’s Alexander’s brand of “election strategy” that leads to gaffes such as Ed Miliband choosing to be filmed in a deeply depressing upstairs kitchenette – the sort of place a prostitute might make a Pot Noodle – in case his real kitchen blasted away the public’s trust with its sheer opulence: the mood-lit wine fridge, the live lobster tank, the unicorn ivory worktops, or maybe just the fact that there’s an actual chair.

Douglas Alexander is saying that Cameron should not have answered the question at all … Photograph: Ken McKay/ITV/Rex

Criticism of Cameron’s candour didn’t only come from other parties. Many Tories believe it was a strategic blunder – that he might now be seen as a “lame duck”. One anonymous former minister said: “This was peculiar and unnecessary. It does not help the prime minister’s authority.” While another Tory apparently remarked: “This was an ‘Oh fuck’ moment. The best you can say is David is straight and honest.” The implication seems to be that calling a prime minister honest is somehow damning with faint praise. I’m not at all sure that Cameron is particularly honest, but I have no doubt he’d be more popular if everyone thought he was.

This all culminated in a widely reported “damage limitation exercise” in which Michaels Fallon and Gove went around saying how reasonable and straightforward the prime minister had been. Which was obviously true in this case. But if there’s one thing that can make something reasonable and straightforward seem otherwise, it’s some oleaginous loyalists touring the media repeatedly saying it’s reasonable and straightforward. And it smacks of panic – as if a secret the-prime-minister-has-actually-answered-a-question alarm had gone off in Downing Street for the first time since Churchill brought up “blood, toil, tears and sweat” instead of hard-working families.

This nasty little Westminster squall is a good illustration of what’s wrong with British politics at the moment – of the tedious and irrelevant scrutiny of image and tactics that we’ve somehow adopted instead of a properly functioning political system. We get a tiny glimpse of openness and humanity, of the prime minister talking like a normal person, and it’s immediately stamped on.

The other parties can’t restrain themselves from making political capital out of it, from attempting to twist Cameron’s completely apolitical remark into something that exemplifies what a bastard he is. They can’t just leave it alone and talk about policies instead. Similarly, the grumbling Tory backbenchers can’t suppress their anger that the prime minister has exercised his right to freedom of speech without running it by them first. So they complain that it’s a tactical cock-up.

This kind of row feels so irrelevant to the issue of how best to govern a discontented and divided nation. It’s an insulting waste of the public’s time and attention – of interest only to politicians and politics nerds – and the likes of Douglas Alexander do further damage to our discredited system by resorting to it.