Rishi Sunak has only just been named Britain's PM, and already he is running out of time

Sunak should not pause to celebrate. AP

Just seven weeks ago, Liz Truss took to the podium to deliver a victory speech to her fellow Conservative party members after they chose her over Rishi Sunak to replace Boris Johnson as Britain’s prime minister. Her standoff with Mr Sunak and the other leadership candidates, she noted, showed “the depth and breadth of talent” in the party.

But after weeks of tumult, Ms Truss’s tenure, like Mr Johnson’s before it, gave rise to exasperation from her own party and incredulity from the wider public. And like Mr Johnson’s, it ended in the prime minister’s resignation. Now, it seems, the Conservative party has little appetite to explore the depth and breadth of its talent pool. In a mea culpa that was as striking as it was swift, party members on Monday anointed Mr Sunak as their new leader after all of rivals were pressured to withdraw their candidacies.

Mr Sunak, a former chancellor of the exchequer and an international banker by trade, will know that the party’s chaos, marred by infighting and mismanagement ever since the resignation of David Cameron six years ago, has created an atmosphere of instability that few developed nations could compete with. And it has infected everything from pensions to international trade deals with harrowing uncertainty.

In a mea culpa that was as striking as it was swift, party members anointed Mr Sunak

The mounting disunity within the Tory ranks, exacerbated by the pains of Brexit and the fatigue of 12 years in power, has reached a crescendo. Mr Sunak was the first of four chancellors of the exchequer Britain has seen this year. He is the third prime minister in less than two months. Mr Johnson’s doctrine was characterised by huge spending commitments and “levelling up”. Ms Truss’s by tax cuts for the rich, little to say about how to fund them. Mr Sunak is expected to take a more moderate, traditionally conservative approach, though this has not yet been fleshed out.

The lack of predictability has investors worried. The City of London, historically a safe haven for the world’s money, was already battered by Brexit. Its bankers have, in recent weeks, watched the swinging value of the pound in silent horror. The Bank of England has had to think creatively to staunch the country’s economic wounds.

But Britain’s neighbours are worried, too. Last week, at an EU summit in Brussels, the French and Irish leaders both expressed their hopes that Britain would find “stability”. Dutch Prime Minister Mark Rutte, who was then celebrating 12 years in power, said he was looking forward to working with Ms Truss’s replacement: “It will be the fifth one, I believe.”

As “the fifth one”, Mr Sunak will have an even tougher job than the fourth, the third, or even the second, Theresa May, who was responsible for negotiating a Brexit agreement with the EU. That is because each prime minister from Ms May onward has not only failed to sort out the full mess of Brexit, but also managed to add new messes to its wake – in Mr Johnson’s case, an erosion of the public’s trust, and in Ms Truss’s case an erosion of that of the markets. Reversing all of this is not a quick process, but given the waning political lifespan of those who occupy Downing Street, Mr Sunak can ill afford to take his time.