Theresa May has arrived in India at the start of a three-day visit expected to be dominated by discussions on trade and travel visas in the post-Brexit era.
The New Delhi government has made clear it will put pressure on the Prime Minister to relax restrictions on Indian nationals coming to Britain - particularly students.
But Mrs May's priority is doing the groundwork for a free trade deal between the two countries after the UK leaves the EU, as well as reducing existing barriers to commerce.
On her first trade mission as PM, Mrs May was joined by representatives of 33 companies from around the UK in what she described as an effort to "reboot an age-old relationship in this age of opportunity".
She will speak with some of India's most influential business figures in New Delhi and southern tech hub Bangalore, as well as holding more than two hours of talks with her counterpart Narendra Modi.
Mrs May hopes to secure agreement for official-level talks to pave the way for a post-Brexit trade deal.
But she will face pressure from her hosts about the availability of UK visas for Indian workers and students, amid unease over higher salary thresholds for skilled workers announced by the Home Office just days before her arrival.
Former business secretary Sir Vince Cable said his efforts to forge a UK-India trade deal during the coalition were "screwed up" in part by Mrs May's decision as home secretary to scrap the post-study work visa, which had allowed Indian students to pursue jobs for two years after graduation.
"May in particular was very obstructive of any attempt to make a genuine generous concession, and that was one of the things that screwed up the negotiation," Sir Vince told The Observer.
Indian government spokesman Vikas Swarup confirmed Mrs May would face questions over visas, telling The Observer: "In the last five years or so, the number of Indian students enrolling in UK universities has gone down by almost 50% - from around 40,000 to about 20,000 now. This has happened because of restrictions on post-study stay in the UK.
"We will continue to raise our concerns regarding mobility with the UK. Mobility of people is closely linked to free flow of finance, goods and services."
UK officials said the trip would see commercial deals sealed to create 1,370 jobs in Britain, as well as the establishment of a new UK-India "smart cities" urban partnership with the potential to unlock opportunities worth £2 billion.
"The UK and India are natural partners - the world's oldest democracy and the world's largest democracy - and together I believe we can achieve great things - delivering jobs and skills, developing new technologies and improving our cities, tackling terrorism and climate change," said Mrs May.
"This is a partnership about our shared security and shared prosperity. It is a partnership of potential. And on this visit I intend to harness that potential, rebooting an age-old relationship in this age of opportunity and with that helping to build a better Britain."
Among deals expected to be confirmed during the visit are:
:: A £1.2 million joint venture between the Pandrol Group UK and Rahee Group in India to set up a manufacturing plant for rail projects;
:: A £15 million imaging and diagnostic centre in Chennai by Lyca Health UK; and
:: A £350 million investment from British start-up Kloudpad in high-tech electronics manufacturing in Kochi.
Both governments are also due to sign an intellectual property co-operation agreement, while the UK will commit to extending assistance to help India improve its business environment, which has seen it languish in 130th place in the World Bank's ease of doing business index.
Joining Mrs May on her visit were International Trade Secretary Liam Fox, trade minister Greg Hands, as well as business figures including Standard Life chairman Sir Gerry Grimstone, Standard Chartered chairman Sir John Peace, Diageo chief executive Ivan Menezes and Aviva chief executive David McMillan, as well as a number of small businesses.
Mrs May is also due to pay her respects at the Raj Ghat memorial to Mahatma Gandhi during her stay in New Delhi.