PwC, an accountancy firm with revenues of $35bn last year, couldn’t deliver accurate figures on the 5,700 votes for the Oscars when it really mattered. This was not a mistake that changed the world but it did destroy the appearance of a well-oiled and supremely professional machine, just as thoroughly as if the Queen were to stop to read a text message in the middle of opening a session of parliament. It is enough to make anyone wonder about the role of expertise in the world today. The big accountancy and consultancy firms can charge pretty much what they like for their services. The British government paid more than £1.3bn to consultants in 2015 – and that’s just central government. Some were paid upwards of £1,000 a day, which is a great deal more than most of the civil servants they have replaced could expect. At the same time, what’s left of the state lurches from crisis to absurdity. Whether it is the NHS, the Ministry of Defence, or the prison system, anyone could tell you that the people in charge of the mess now should not be – but if you ask a consultant, that piece of arcane wisdom will cost you plenty more. Brexit, even if it accomplishes nothing else, will enrich the consulting firms and the lobbyists almost as much as it will impoverish the rest of us.

These big companies and the legions of highly paid experts are supposed to be delivering measurable results, yet it seems most of what they touch runs worse than before. So it’s worth asking what it is they are actually selling that is worth so much. The first, obvious answer is plausible deniability. If a management wants to slash its workforce then it is obviously better that the bad news be delivered by outsiders who can be blamed later. This evasion of responsibility may well be worth a great deal to the managers concerned, if not to the other stakeholders of the enterprise. This motive overlaps or shades into another, more interesting one. The one thing that consultancies and even accountants are meant to deliver is objectivity – and from that springs authority, which is what they’re really selling. Someone who comes along with an air of confident command will always find followers even if they know nothing about their subject, providing the followers are more painfully confident of their own ignorance. The vocational education of the English ruling classes taught the art of bluffing at the speed of thought – and though this skill is indispensable at the bar, and still more in the House of Commons, unfortunately it’s not the best way to make really important decisions, as the career of David Cameron so catastrophically demonstrates.

Sometimes the experts actually do know more. It would be wrong to suppose that all authority is phoney just because some is. Even the most doctrinaire economist is sometimes right about some things. But the kind of expertise worth paying for is almost always the least reassuring. Just as a good scientist will answer a question with a clear statement of the limits of certainty as well as of what is in fact known or estimated, a good piece of policy advice is most unlikely to be something that can be boiled down to one weird trick. On the rare occasions when there are simple, obvious facts which should dictate a change of course, the expertise in demand tends to be that which will help people ignore the problem and concentrate on something less painful and easier to control. It doesn’t take a consultant to understand, for example, that the NHS needs more money; but it takes a very special and expensive skill not to understand it.