David Cameron has mounted a charm offensive on India, allowing it access to British nuclear expertise for the first time and sharply criticising Pakistan's record on terrorism.
The Prime Minister called for a new era of co-operation between the UK and India as he led a delegation of British ministers and business executives to Bangalore and, later, New Delhi.
Appealing for deeper trade ties that will fuel jobs back home, he also sought to demonstrate that India stands to gain from a closer relationship with Britain.
His visit coincided with the announcement that, in future, export licences for civil nuclear expertise and technology to India will be approved, a move that will not only please the Indians but UK firms involved in nuclear research, such as Rolls-Royce and Serco.
Whitehall has traditionally vetoed such co-operation because India has not signed the Nuclear Non-Proliferation Treaty or separated out its civil and military programmes.
Mr Cameron also sought to address Indian concerns about terrorism, particularly from its neighbour Pakistan.
In forthright comments that angered Islamabad, the Prime Minister warned that Pakistan must not be allowed to "promote the export of terror" to the world and said he will be raising the issue with Indian prime minister Manmohan Singh when they hold talks in Delhi on Thursday.
He described India, by contrast, as "responsible" and backed calls for it to be awarded a seat on the United Nations Security Council.
A new agreement between BAE Systems, Rolls-Royce and Indian aerospace company Hindustan Aeronautics Limited (HAL), to provide India with 57 more Hawk jets, was also announced.
Visiting HAL's Hawk facility in Bangalore, Mr Cameron hailed the £700 million deal as an "outstanding example of India-UK defence and industrial partnership".