DE gustibus non est disputandum is one of those snappy phrases used quite a lot and, as a consequence, thought true, when in fact there’s plenty disputare about it. We usually regard it as equivalent to chacun à son goût which, for some reason, is the way English speakers render the French phrase à chacun son goût, but the Latin says something slightly different. Rather than “each to his own taste”, it’s that there is no basis for arguing about taste, which is not quite the same as saying “there’s no accounting for taste”.

One example of this is the impulse, so popular on the internet, to draw up lists of “the best” or “the worst”: science fiction films, crime novels, bubblegum pop songs, biscuits or what have you. These are always a draw, because people can’t resist the opportunity to tell you that you’re a moron for putting Solaris higher up the list than Blade Runner or vice versa.

The other day, in a Twitter dispute over best gangster movies, someone said that Goodfellas was probably the greatest, but he personally preferred Casino. It strikes me that this is an example where you can’t argue about the taste; I can’t make you enjoy one more than the other. And while you could argue about the ranking, it’s not as if there is a “correct” answer.

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All the same, such lists, even if never objectively accurate or universally agreed to, clearly do have some relationship to external truth. As long as people agree on what the premise and the criteria are, it’s easy to regard some top tens as reasonable – even if they’re not what you would have picked – and others as downright insane.

I was thinking of this because today marks the fifth anniversary of Theresa May’s installation as Prime Minister, and I was wondering whether she was the worst ever, or at least in living memory. But then I remembered that, naturally enough, it also marks the fifth anniversary of David Cameron’s resignation as Prime Minister, and immediately thought that he could give her a run for her money for the title.

Both would surely be high up on anyone’s list. The first thing to get out of the way, when considering whether there’s any merit in trying to make the judgment, is what you mean by “worst”. Lots of people regard Margaret Thatcher as the worst PM, because they hated her and her policies. There are also quite a few people who loathe Tony Blair, including the polar opposites of reactionary Tories and members of the hard Left.

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Most assessments of success or failure, however, aren’t judging that sort of thing, if they aim to provide a plausible case; they’re about whether the time in office was effective, significant, electorally popular, or transformative, not about whether you like what a PM did.

Thatcher and Blair were both successful in those terms. A list that puts Churchill (in wartime) or Attlee high up is plausible: one that rates Douglas-Hume or Heath isn’t. The general consensus is still, I think, that Lord North was even worse than either Lady May or Mr Cameron, because he was in office when Great Britain managed to lose the American colonies. You would have to be a particularly crazed sort of Remain supporter to argue that Brexit, even if it turns out very badly, can compete with that sort of foreign policy blunder.

American independence turned out for the best, though, and North was actually in office for a long time and did quite a lot of other things, so perhaps the judgment is harsh. In recent history – say post-war – Eden and Heath would probably be the highest-scoring as failures (though Churchill was a poor peacetime PM, and I think neither Major nor Brown did at all well) but a plausible case can still be made for both Mr Cameron and Lady May as worst.

The reason, naturally, is Brexit. But not necessarily because Brexit was a mistake. As Zhou Enlai was said to have remarked of the French Revolution, it’s too early to say. (Ruining a good story, it’s now thought he misunderstood, and was talking not about 1789, but les événements of 1968.) In any case, the responsibility for Brexit, whatever you think of it, lies with the public.

The case against Mr Cameron is that he created the referendum, that doing so was a reckless error, and that he then complacently mishandled the Remain campaign, and ran off, leaving everyone else to sort out the mess. The case against Lady May is that, having undertaken to get the measure through (though she had herself opposed it) she bungled everything, created constitutional gridlock, threw away her own majority and left us with the worst of all possible worlds.

Of the two, I think the charges against Lady May are worse. Mr Cameron had, after all, the promise of a referendum in his manifesto. Those who say he did so only to placate rebellious backbenchers and see off competition from Ukip are missing the point: it almost certainly helped him to win the election, so by definition it was a policy much of the electorate wanted. As an advocate for Remain, he should certainly have taken the risk more seriously, and was useless in campaigning, but his errors were essentially democratic – as was his inevitable resignation.

His successor, by contrast, generated most of her blunders by herself. She made no attempt to investigate options such as staying in the EEA or Efta, since she thought the referendum was about immigration (because as Home Secretary, that was “her” issue). She called a snap election to increase her majority and improve her mandate, then lost it. She never got any of her measures passed, because she never amended them in any useful way. She certainly faced intransigent, and often astonishingly anti-democratic, opposition from both sides, but the fact was that she offered nothing anyone wanted, and kept obstinately doing so.

It is difficult now to believe that she was new, and surprisingly popular, just five years ago, or that she was still in office less than two years ago (she resigned on July 24, 2019). It’s a shame they can’t both be judged worst ever, really. But it’s not too early to make the judgment. Lady May was an out-and-out disaster.

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