Where does influence lie in British politics these days? Not just in Westminster and Whitehall. One of the most notable features to emerge in recent months has been the influence of a few prominent individuals from outside the formal political orbit.

I’m talking about Jamie Oliver and Sir David Attenborough. The former – in concert with Hugh Fearnley-Whittingstall – has exploited the power and activity vacuum prompted by Brexit inertia and Government paralysis to galvanise the campaign for a more interventionist approach on childhood obesity. The latter has used his national treasure clout to spearhead a revolution against single-use plastic, making the traditionally fringe matter of the environment mainstream for the first time in decades.

With No.10 preoccupied by Brexit, the 2017 Queen’s Speech signalled a significant lull in domestic policy. Into this legislative gap Oliver and Sir David have successfully managed to fit their agendas.

As a consequence of the highly effective celebrity-fuelled campaign on obesity, the Government now looks set to clamp down on two-for-one promotions for HFSS (high fat, salt or sugar) foods and potentially introduce a new, more restrictive watershed for HFSS advertising. It’s clear that not everything is on hold. In just a matter of months or even weeks, ministers have gone from emphasising that the 2016 childhood obesity strategy was sufficient to – reportedly – backing the majority of measures proposed by Oliver and his public health lobby supporters.

Meanwhile, plastic packaging – a subject that just a year ago was only a peripheral concern, pushed by the likes of Prince Charles and a number of charities – has become the cause célèbre of British politics in 2018, with businesses falling over themselves to announce far-reaching action on recycling and waste reduction. Last week the Treasury revealed that it received 130,000 responses to the consultation on single-use plastics – the largest ever response to a public consultation for the department. In Defra, coffees are now drunk from refillable cups; MPs enthusiastically embraced the challenge to give up plastic for Lent. To give him his due, Michael Gove started pushing this agenda at the 2017 Conservative Conference, but the issue only became front page news when Sir David gave his endorsement during Blue Planet II.

Politicians like nothing more than a populist bandwagon, and in both cases, these causes have been further propelled to the top of the policy agenda by pressure from the devolved administrations and the London mayor, and by major newspapers and broadcasters getting behind them. And on both, key departments are now understood to be on board, with the Mail reporting that Brexit arch-rivals Gove and Chancellor Philip Hammond are working together to push for taxes and restrictions on disposable goods. Furthermore, on obesity, January’s reshuffle saw Matt Hancock become Culture Secretary; unlike his predecessors he is understood to be less opposed to restrictions on advertising. As an ambitious politician, he doesn’t want to be perceived to be on the wrong side of the public debate.

Theresa May may be a less image-focused prime minister than most of her recent predecessors, but living day-by-day on a slim Commons majority, she is highly susceptible to the weight of public opinion. Given the limitations of the Government’s majority, it’s hardly surprising that when her team sense a groundswell of support for the messages being pushed by the Naked Chefs and national treasures of this world and applauded by the press and public alike, they embrace it with open arms. Campaigners championing other such issues – for example easing the restrictions on abortion in Northern Ireland, or lifting the visa cap on in-demand skilled workers like doctors – would do well to take note.

Whether celebrity-fuelled policymaking leads to good, evidence-based legislation is a different matter. Some critics, for example, suggest a deposit return scheme – a solution promised by the Government to tackle disposable bottle usage – could distract funding from kerbside recycling and won’t achieve the reduction ministers are hoping for. Likewise, the causes of obesity are understood to be complex; clamping down on HFSS advertising on television could simply push this to other platforms. Opposition parties have little to gain by resisting measures that are popular with the public. Given the state of Westminster right now, many of these policies are likely to be pushed through unchallenged.

While No.10 seeks to navigate the stormy waters of Britain’s future relationship with the EU, the current political climate for campaigners there is everything to play for – provided they can get the public and especially a few prominent, media-savvy public figures on side.