When Keir Starmer wanted to inject a moment of levity into his first speech as prime minister at the Labour conference, he told a story about visiting a holiday cottage in the Lake District where the owner joked about wanting to push him down the stairs.

As lighter moments go, it had a dark edge. It is British humour, of course, but there is a reason it made an impression on Starmer – it’s a microcosm of what he and his closest advisers see as their greatest threat: the cynicism and disdain with which ordinary people view politicians. The view that they are all the same, all on the take. The widespread lack of trust that politics can make lives better.

In part, it is this very sentiment that caused voters to turn against the Conservatives and deliver Labour’s landslide victory. But given that Starmer and Labour are politicians too, this sentiment is not their friend.

Starmer has become unapologetically the un-populist prime minister, who urges difficult trade-offs to make the country more prosperous and fair.

The new homes needed on green fields for working families, the electricity pylons needed to deliver clean energy, the building of new prisons to prevent a repeat of the need for early release schemes, and a hint of the tax rises to come in October’s budget to fund essential public services.

The speech was billed as the moment that Starmer would reach for optimism – although in the end this was something of a stretch. Sunshine is never quite this prime minister’s style.

“Change begins”, as the slogan for the conference goes, but the postscript should be: “It is difficult, it takes time and it may have side effects that not everyone will like.”

Is that optimism? Yes, Starmer argues. For him, that gear shift was about seizing the moment to talk about the promise of change in detail, not just sweeping rhetoric, as he reeled off what the Labour government has already achieved, from renters’ rights reform to onshore wind and rail nationalisation – the policy that drew the biggest whoops and applause in the conference hall, full of the home crowd.

There was some new detail: a promise on social housing for veterans and domestic violence victims, as well as the Hillsborough law. But at its heart the speech was about pledging anew to fulfil the promises he made in the election campaign and begin the renewal that he unashamedly says would take a decade in power.

The speech was at its most powerful when the prime minister made the case against the two sides of the populist coin.

First he attacked the opportunist grifters – without mentioning politicians by name – who equivocated on the August riots and linked them to legitimate concerns about immigration. “This country sees you and it rejects you,” he said.

For many it will be powerful that he has returned to that topic and the deep unease it created in communities about the state of the nation.

But the other side to populism is what Starmer called in his speech “the politics of easy answers” and it was the main thrust of his prosecution of the Tories’ record in power.

He argued that the Conservatives, who promised so much with none of the trade-offs, are responsible for that breakdown in public trust. Longer sentences without ever building prisons, or deportation flights to Rwanda while asylum backlogs pile up. He could have mentioned Brexit, although he didn’t.

Starmer’s answer to that degradation of politics was honest, interventionist government, which would mean hard choices but material improvement.

The new prime minister is already haunted by what is at stake if Labour gets this wrong over the next five years. There are frightening lessons from all over Europe about what that means.

The government vowed in the king’s speech to be the antidote to the “snake oil charm of populism”. The cure, ministers believe, can only be serious government, delivery, honesty about the trade-offs needed and tangible change to the lives of ordinary people.

But unsaid is that this is one of the reasons why the row over donations for clothes and entertainment cuts so deep.

Starmer does not believe politicians are all the same; it is a refrain that irks him more than any other. He knows he is different from Boris Johnson. There is immense frustration he has allowed misjudgment to give his political enemies an opening to make the claim that they are similar.

Should he ever return to his Lake District holiday cottage, one small measure of success would be whether his host complains to him about pylons or makes a joke about his suit.