Sir Keir’s pledge to clean up in politics will come back to mock him if he doesn’t deliver | Andrew Rawnsley

Sir Keir Starmer is prime minister presumptive. Unless the polls are more wrong than they have ever been or there is a sensational late shift in opinion the like of which we’ve never seen, in five days’ time he will be delivering his first speech to the nation from Downing Street. If he follows the model of predecessors, he will introduce himself as PM by making solemn undertakings “to repay your trust”.

That was the phrase used the day after the 2019 election by Boris Johnson . He then went on to demonstrate that the only thing he could be relied on to deliver was serial mendacities. If Sir Keir proclaims that he will prove worthy of the country’s trust, he had better be believable. Given the grimness of the inheritance about to land in Labour’s lap, and the time it will take to grapple with it, he will need to persuade the public to give him the benefit of the doubt that his plans will reward patience.

Trust is a precious commodity in politics and now so rare that this election has been devoid of it. Time and again, on doorsteps and at hustings, voters have expressed withering contempt for politicians. Time and again, the politicians have suggested that they do not think voters can be trusted to handle the truth about the challenges facing Britain by swerving the crunchier choices and grittier trade-offs that will confront the next government. The mood of the electorate is sullen and suspicious about the political class as a whole. One spectre haunting Labour’s team is that its victory will be marred by a depressed turnout because many voters are too alienated to bother to cast a ballot. One of the more candid remarks of this campaign came from Wes Streeting, the shadow health secretary, when he acknowledged that public trust in politicians is “ at rock bottom ”. The polling evidence says he is correct. The latest British Social Attitudes report finds that trust is at its lowest point in the survey’s 41-year history. A chunky majority now say they “almost never” trust politicians of any party to tell the truth when they are in a tight corner.

Public deference started curdling into disdain some decades ago, but never before has it reached such extreme levels. Even before the betting scandal provided yet another reason for voters to wrinkle their noses in disgust, distrust was the primary dynamic of this election. Knowing how very few voters are prepared to believe anything said by the Tories, Rishi Sunak has concentrated his effort on trying to suck his opponents down to the same level by stoking distrust in Labour. Knowing how deep runs the electorate’s wariness of politicians bearing promises, Labour has emphasised the modesty of what it thinks it will initially be able to do with power. Smaller parties also have their trust issues. Nigel Farage’s boast to be the “straight-talker” has been exploded as the fiction it always was by his desperate wriggling about the extreme and vile bigotry of members of his fan club. Nine years on since the termination of the David Cameron-Nick Clegg coalition, there are voters still making Sir Ed Davey wince by reminding him that the Lib Dems broke their promises on tuition fees. From turning Number 10 into a law-breaking drinking den during the pandemic to dishing out lucrative Covid contracts to their mates, repeated scandals have been a vote-shredder for the Tories. But it is not their problem alone. Criminal charges against high-profile figures are casting dark shadows over the SNP in Scotland and the DUP in Northern Ireland while Labour squirms over a donations controversy in Wales.

Policy failure after failure has corroded confidence in the capacity of the state to rule wisely and well

Little wonder that a lot of voters say a pox on all of them. At the last of the Starmer-Sunak head-to-heads on TV, the first questioner from the audience asked: “How would you restore trust in politics?” Sir Keir’s answer is a promise to “reset” and “clean up” politics to ensure “the highest standards of integrity and honesty”. One of his applause lines is that he will “ return politics to public service ”. Those pieties will come back to mock him if he doesn’t deliver. His allies insist he means it. “For Keir, this is very important,” says one member of the shadow cabinet. “He has very high expectations of people and woe betide anyone who lets him down.”

The crisis of trust is hydra-headed, each branch beginning with a P. Policy failure after failure has corroded confidence in the capacity of the state to rule wisely and well. Public institutions have repeatedly betrayed the public’s trust, as vividly illustrated by the atrocious treatment of the victims of the Windrush , contaminated blood and Post Office Horizon scandals. Added to which is the perceived plunge in the ethical calibre of parliamentarians. Today I will focus on the people dimension because that will be the most searching personal test of Sir Keir’s commitment to higher standards.

Any account of the crisis of trust must highlight Boris Johnson, the first person in our history to have occupied the position of prime minister and been found guilty of lying to parliament by the Commons before being impelled to exit the building. Grotesque as that was, he didn’t bring the last parliament into disrepute all by himself. He was an especially rotten apple, but he wasn’t the only bad fruit in the barrel. Public repugnance has also been accentuated by the record number of cabinet ministers fired or forced to quit for misconduct and the unprecedented number of backbenchers – mostly, but not exclusively, Tories – who were suspended, expelled or compelled to quit in the course of the last parliament. The new parliament elected on Thursday will have the chance to make a fresh start because there will be a big turnover. The next Commons will be younger and packed with first-time MPs, thus far untainted by scandal. This provides an opportunity to improve the reputation of politics, but it doesn’t mean that the age-old temptations of power are simply going to vanish. The new parliament will have its share of the feckless, the reckless and the rapacious. Anyone naive enough to think a Labour government will be a choir of angels has never seen a previous one. If Labour wins big, it will have a lot of MPs without government jobs. Idle hands can be the devil’s playthings.

There are several things Sir Keir can do to establish deterrents against dissolute behaviour. Quick steps right at the start of his premiership will be an excellent way to provide a demonstration that Britain is under new management. It ought to please Rachel Reeves that valuable reforms can be introduced without costing the exchequer a penny. A good start would be to significantly toughen the safeguards to prevent abuses in lobbying and public appointments as well as beefing up the restraints on people moving from roles in government to employment by commercial interests. Labour could call that “Cameron’s Law”. We don’t need more toothless watchdogs. The ethics and integrity commission proposed by Labour needs to be genuinely independent and armed with the clout to impose meaningful sanctions.

Another early priority ought to be strengthening the ministerial code and empowering the invigilator to initiate inquiries and publish findings without interference from Number 10. Some people around Sir Keir are nervous about creating a stick they fear could be used to beat them. They need to be told that unflinching reform is a must if public confidence is to be rebuilt. If the Labour leader means it when he says he will “lead from the front”, he will establish a “zero tolerance” culture towards sleaze and any other form of misconduct. As proof of his steel, Sir Keir likes to cite the summary suspension of the Labour candidate who admitted to betting on himself to lose. Truth to tell, that proves little. It wasn’t a terribly hard decision to disown a hitherto obscure candidate in a non-battleground constituency.

The searching test for Sir Keir will come when one of his ministerial team disgraces standards in public life. He talked tough to his biographer, Tom Baldwin, when the Labour leader said that “people will only believe we’re changing politics when I fire someone on the spot”. What if the miscreant minister is popular in the party? What if they are a senior member of the cabinet with their own powerbase? What if the offender is one of the prime minister’s close allies? The most revealing test of his moral fibre will be when we see how he deals with transgressive friends. This will define how truly committed he is to integrity and honesty.

“Cleaning up politics” is one of the easiest things to say from opposition. It will be one of the hardest things to do in government.

• Andrew Rawnsley is the Chief Political Commentator of the Observer