It’s not often that hush-hush conversations along Whitehall turn into a discussion of Karl Popper’s The Open Society and Its Enemies – but they did during the last Parliament.

There I was talking to a government adviser, making notes in my head, when he suddenly started explaining the Coalition’s reform agenda by way of that great book. They weren’t going in for what Popper called “Utopian social engineering,” he said; chasing a big, abstract idea of how all society should be. Instead they were practising the good professor’s preferred “piecemeal social engineering”; trying to improve things bit-by-bit.

This suggested something about the last Government, I thought at the time, beyond just what form of social engineering they were into. It suggested just how bookish they were. Not “bookish” in the sense of horn-rimmed spectacles and cosy libraries. But “bookish” in that there was always a book behind what they were doing. It felt like government by literary reference. Writers became our unelected legislators.

The books weren’t just old ones from over 60 years ago. There were more recent ones too. David Cameron held up a copy of Daron Acemoglu and James Robinson’s Why Nations Fail, which argues for the importance of institutions. George Osborne was influenced by Robert J. Shiller’s Irrational Exuberance and, one co-authored with George A. Akerlof, Animal Spirits. The Cabinet Office was guided by Cass R. Sunstein and Richard H. Thaler’s Nudge. Everyone feared the return of one of Nassim Nicholas Taleb’s black swans.

I could go on, but you know the sorts of books I mean. They are the ones that occupy the Politics & Society section in Waterstones. They have authors who are invariably called “gurus”. And, for most of the last Parliament, there was always one to hand for answering, at least in part, that persistent question: what are Cameron and Osborne really up to?

Which brings us rubbing up against another question: what about now? One small way in which politics has changed is in the decline of these manuals for governance. This isn’t to say that there aren’t books which influence our legislators and their advisers. There are. But none really have the prominence or pervasiveness of the ones listed above. With the exception of Thomas Piketty’s Capital in the Twenty-First Century and other titles from the left – which aren’t exactly well-thumbed by Conservative ministers – it’s the biographies that have come to the fore.

This small change has been brought about by larger, historical ones. Several of the books that informed the Coalition were written in response to the Crash (Irrational Exuberance, Animal Spirits, The Black Swan). Others were useful for governing without much money (Nudge). Others still, such as Phillip Blond’s Red Tory or Nick Boles’s Which Way’s Up?, were effectively commentaries on the rise of the Conservatives and where they should go next. None of these things have become irrelevant, but they are no longer quite so urgent. Time has moved on.

The sad truth is that many of yesterday’s Big Ideas become today’s footnotes – and most people ignore the footnotes. Nudge Theory is a good example of this. It was novel and exciting up until (or just beyond) the point where the Behavioural Insights Team was established, Richard Thaler was brought in as an adviser, and the whole thing was subsumed by government. Now it’s just a part of the everyday.

Which is a roundabout way of saying that politics settles. Once a government has gone through the intellectual process of deciding what it wants to do – whether it has made the right or the wrong decision – there’s not much left but to get on with doing it. The books are put aside and replaced by hand tools. Or, in terms of Downing Street personnel, Steve Hilton is replaced by Lynton Crosby. And what does Hilton do? He goes on to write a book that will appear alongside all those others in Waterstones, of course.

As for Crosby, his influence on the Tory leadership shouldn’t be overstated. The Crosbyisation of the Government was always part of a general movement towards simpler, doorstep policies. Out went the Big Society. In came the Northern Powerhouse and welfare cuts and apprenticeships. These policies don’t get done with hifalutin’ books; they never required books in the first place. All that’s needed is some good, old-fashioned hard work.

Perhaps this is the main reason for the decline of the gurus. Not only have Cameron and Osborne now decided how to dress this Government, but they’ve also decided – more or less – on a blue collar. It’s straightforward and it appears to win elections. American academics need not apply.

Or perhaps they’ve simply taken Karl Popper’s words to heart. All Utopianism is erased. What remains is the piecemeal task of reducing the deficit whilst satisfying as many voters as possible. Now, that really would be going by the book.