It feels around a hundred political lifetimes ago that a bald, “blue-sky thinker” called Steve Hilton was padding around 10 Downing Street in his socks, excited by a new bestselling book on the relatively new discipline of behavioural economics, called Nudge.

The case study everyone recalls from that 2008 book, by two American behavioural economists called Richard Thaler and Cass Sunstein, was that Amsterdam Schiphol airport had drastically reduced spillage in the men’s urinals by etching a very realistic drawing of a fly next to the plughole.

Jet-setting gents relieving themselves suddenly had something to aim at. It was a simple, cheap and frankly ingenious solution to a problem, that involved subtly persuading people to change their behaviours – giving them a nudge.

This kind of thing had obvious appeal to a newly elected Cameroon Conservative party, with metropolitan elite credentials, absolutely no money to spend and a T-shirt wearing strategist with cool credentials that needed justifying.

The Nudge unit was born, or to give it its proper title, the Behavioural Insights team. Back then, in those simpler times at the start of this decade, clever ways to improve the implementation of government policy were what counted as a big deal.

Conservatism is not so cool these days. No one is hugging huskies. Steve Hilton is long gone, off to Silicon Valley from where he occasionally goes into bat for Donald Trump on Fox News, or dials to Newsnight to bemoan the malign influence of “elites” in the Britain he and his Google and Uber executive wife left behind.

But the Behavioural Insights Team is very much still going. It has even become a social-purpose company, providing its canny insights to governments around the world.

So what of nudges in an age of political earthquakes?

“The Nudge unit fitted with the David Cameron and Steve Hilton narratives,” says its director Dr David Halpern, in his glass walled office in Westminster, which just so happens to be in the same building as Conservative Central Office.

“But it has itself evolved now. It has matured. It has matured beyond the way it was used in those days. It is less high-profile than it was, because for David Cameron and Steve Hilton it was almost emblematic to be able to say, ‘You can do government in this different way.’”

In those days, its early days, it achieved notable successes like altering the wording used to encourage organ donation, and 100,000 more people a year started to do so.

Outside his office, Astroturf lines the walls. A staff whiteboard lists the dates of “film club” and “fun Friday drinks.” Dr Halpern is a policy person, not a political person. In his pre-Nudge days he was a founding director of the Institute for Government, and before that an experimental psychology professor at Cambridge.

“We actually do much more by volume now we did back then,” he says. “But, as you know well, there’s a lot else going on in the political narrative.” That there is a lot more “going on in the political narrative” is the closest he can be persuaded to venture into an opinion on the current political quagmire. Quite what a Nudge unit might do under a Jeremy Corbyn government is a question he deftly swerves on many occasions.

“We might have moved beyond being be the top novelty thing, but that doesn’t mean we’re not doing anything. It’s not as mainstream as it was, but it’s not far off. At least 10 departments have Behavioural Insight teams now.”

Some of its successes are startling. For decades, universities have struggled with the challenge of widening access, of convincing capable and qualified pupils from disadvantaged backgrounds to pick up a Ucas form and apply to universities that are only too happy to take them.

An undergraduate at Bristol University called Ben wrote a personal letter, aimed at pupils from ordinary backgrounds who had done well in their GCSEs, telling them in straightforward fashion that universities were desperate for students just like them. They were all handsigned and sent to thousands of such pupils, via their schools, early in Year 12. Two years later, the pupils who’d received these letters were 34 per cent more likely to be enrolled at a selective university than those who hadn’t.

“It’s not quite so snappy as it used to be. Not so ‘oooh, neat little nudge.’ It’s now less catchy, in that Steve Hilton way. But what we do now is much more wide-ranging.”

Halpern won’t talk about Brexit, other than to say the Department for Exiting the European Union is, “Not a big part of our work, let’s put it that way.” But he is keen to stress that away from the glare of the spotlight the nudge unit once had, life goes on.

“Governments have still got to carry on doing lots of things, day in and day out. And in an interesting way, in a funny kind of way, we have more work to do now because one of the primary routes to doing normal government is shut off. It’s not possible to push through legislation. There are far fewer green papers, white papers and so on going through.

“But you still want to make progress on, say, obesity, or the ageing population, or cyber risks, there are still a million things going on.”

Think what the Behavioural Insights Team was built for, he says. “To find alternative policy solutions when you haven’t got alternative levers or legislation, or when you haven’t got much money. The actual environment we’re living in: it’s exactly that.

“It’s not high-profile because it’s not Theresa’s thing. It’s not Steve Hilton saying ‘Oh look at this supercool shiney thing.’ Now it’s more, ‘Ok, let’s use this thing.’”

And in what Dr Halpern calls the “Brexit environment” (in which “the political system and parliament is so lucked up with this one thing”) actually giving departments an alternative ways of getting things done is popular and effective.

“Take productivity. A massive issue. What can we do to keep the dials moving? Departments can come to us and say what you can do to help us given other routes are shut off?”

Rather than any specific policy success, Halpern characterises the Nudge Unit’s greatest success as having “smuggled into government a much, much tougher, empirical approach to policy.”

The precise innovation he has smuggled in, as he puts it, is the randomised control trial. All nudges, including those letters to sixth formers, are measured against a control group who remain un-nudged, so the benefits can be precisely measured, and honed later down the line.

This is routine stuff in scientific experiments, but not so much in government policymaking. When a government introduces a new law, like the sugar tax for example, it impacts everyone at once, from day one. From a scientific perspective, this makes its success or failure much harder to gauge.

But this mini-revolution in evidence-based policymaking comes at a time when it seems as if the world, or least Britain and America seems to be turning away from evidence, and towards at best ideologically driven policy, or at worst emotion based. Even leaving Brexit and Trump aside, Theresa May had not been Prime Minister for more than a few weeks before the prospect of a return to grammar schools returned. Academics do not agree on much, but there are virtually no educational academics who think that the return of the grammar school would do what its proponents claim they do, which is to boost social mobility.

Governments spend “billions on things and have no idea if they work” says Halpern. “I mean, Oh my god. When you someone writes the history of the BIT, the cool ‘nudge’ bit will not be the most significant thing. It will be that the BIT helped introduce an empirical- and evidence-based approach to policy in government.”