I’m sure that, just like me, you learned the hard way when telling your first elaborate lie at school. It didn’t end well, as it led to more lies. Most responsible people learn these lessons young, and do not carry them into their professional life. Sadly, the same doesn’t seem true for today’s government.

I have always been proud of our UK’s strong democracy and fact-based debate. Brexit changed this, and our government entered a game of lies and coverups on steroids. As the debate of whether we should or should not “do Brexit” started, I remember being very confident about entering the debate, as I was sure that the facts would matter most. I was wrong. As we now know, the facts – certainly as far as the economy is concerned – were largely ignored.

“There will be no border in the Irish Sea,” we were told. “There will be no friction in trade with the EU;” “there will be no shortage of labour.” I was sure that the facts would soon emerge and the lies would crash down. But the lies kept coming. We heard the argument that we could deregulate our markets, reduce taxes and still meet all our obligations to climate change and the environment. We heard the argument that we could deregulate yet maintain the highest standards of worker protection. And we heard about the increasing coverups, about illegality, and how badly our underlying economy was performing – not to mention the very elaborate action to cover up the party culture at the heart of government.

The reality is that years of lies, policy blunders and incompetence have severely damaged the UK’s reputation. Credibility is the cornerstone of the UK’s licence to operate in international markets. And the next government – whatever shade that will be – must focus on rebuilding the UK’s global reputation. There are a number of steps we can take to do this, including having a transparent and long-term economic vision that marries fiscal discipline with a long-term green industrial policy that the UK can lead globally.

There is another policy option that no one yet has the confidence to reverse, and that is to rejoin the single market and customs union. It was the biggest lie of them all: that we could replace the economic upside of being part of the most advanced free-trade zone in the world. No independent trade deal can replace its economic upside. It is time to face up to this as a country.

This does not mean opening a debate about rejoining the EU. That ship sailed some time ago. But there is a new possibility. The EU has held out an olive branch: to join a grouping of European countries that don’t want to be part of the EU but do want to benefit from its single market and many collaborative bodies.

This in my view is a perfect moment for our new prime minister, Rishi Sunak, to pivot and send a clear signal globally that we have listened and learned, and that we are going to take sensible steps to restore our reputation for pragmatism and economic sensibility. This would mean not pandering to the European Research Group and rightwing thinktanks, which have been instrumental in much of the chaos of recent months and weeks. Politically it would be a brave shift, and economically a very pragmatic one. In doing so we would be able to re-engage in markets across Europe and start a new responsible growth coalition that we can be all be proud of.

It’s an idea whose time has come. The Liberal Democrats believe in it. Labour needs to pivot to it. But the Conservatives have power and Sunak, new in office, has power, authority and goodwill. This would be putting those three attributes to good use.

• Jürgen Maier is vice-chair of the Northern Powerhouse Partnership, co-founder of the social enterprise vocL, and a former chief executive officer of Siemens UK