Rishi Sunak has arrived in Delhi for the G20 summit - a meeting of leaders from the 19 biggest economies in the world plus the European Union.
He becomes the first prime minister of Indian heritage to visit the country.
No 10 say the "historic" visit will be "a powerful reminder of the living bridge between the two countries".
Mr Sunak is accompanied by his wife Akshata Murty, who was born and grew up in India and is the daughter of one of India's richest men.
The G20 is something of a diplomatic blancmange. Many of the members of it have very little in common beyond big economies.
But that is the point of it - bringing together those countries that are the engine room of the global economy.
The G20 is a child of the 21st Century - conceived in 1999 and growing in stature after the 2008 financial crisis.
It means the discussions within it are often very broad. But the get-together also gives the chance for leaders to meet one on one, in what are known as "bilaterals".
Speaking on the way to the summit, Mr Sunak said he was "excited to be back" in India, calling it "a country that is very near and dear to me".
He said: "It's obviously special. I saw somewhere that I was referred to as India's son-in-law, which I hope was meant affectionately!"
Two of the most powerful men in the world were on the guest list, but aren't turning up.
Russia's President Vladimir Putin will be missing, for the second year in a row.
"Once again, Vladimir Putin is failing to show his face at the G20," the prime minister said.
"He is the architect of his own diplomatic exile, isolating himself in his presidential palace and blocking out criticism and reality.
"The rest of the G20, meanwhile, are demonstrating that we will turn up and work together to pick up the pieces of Putin's destruction."
But it is more complex than that.
President Xi of China isn't coming either. And some G20 members are a lot less committed than others to Ukraine.
The hosts, India, for a start, continue to buy lots of oil from Russia.
The PM refused to say whether he was planning to meet Chinese premier Li Qiang during the summit.
He told reporters on the flight he was "expecting to see a range of people… over the course of the couple of days we're all there" but refused to say whether he would meet face to face.
Free trade talks
The prime minister will meet Indian Prime Minister Narendra Modi, where it is likely they will talk about a UK-India free trade agreement.
There is increasing optimism a deal can be reached soon.
India's Finance Minister Nirmala Sitharaman said she hoped it would be done before the end of the year.
Downing Street has refused to be drawn on a timescale and Mr Sunak said a deal was "is not a given".
His predecessor-but-one former Prime Minister Boris Johnson, had said in 2022 that he wanted a "deal by Divali", but Mr Sunak said: "These things are a lot of work and a lot of time - that's why I've never put artificial deadlines on these trade deals.
"I've always said we shouldn't sacrifice quality for speed."
India's desire for visas with more flexibility has long been seen as a potential sticking point in the negotiations.
The prime minister's official spokesman told us: "This is a trade deal which is focused on trade and business - immigration is a separate issue.
"The only aspect of the movement of people covered by a free trade agreement is business mobility, which is the temporary movement of business people for specific purposes."
Shadow foreign secretary David Lammy said the Conservatives had said the trade deal "would be completed by last October" and claimed Mr Sunak "arrives at the G20 as a minnow on the global stage".
Ahead of his trip, the PM came under pressure from MPs to raise the case of British man Jagtar Singh Johal, who has been in prison, on death row, in India.
Mr Sunak twice refused to commit to raising the issue with Prime Minister Modi.
But for all the politics, and diplomacy, the early focus of this trip will be pictorial, symbolic and drenched in history - a British prime minister visiting a former British colony.
A British prime minister of Indian heritage, as India hosts the world - or at least a huge economic chunk of it.