Seeing the back of US President George W. Bush was always going to be tinged with regret for New Delhi, after he helped India score one of its biggest foreign policy advances in decades only last month.

Manmohan Singh, the prime minister, famously told Mr Bush on the eve of an agreement to bring India’s nuclear programme out of international isolation: ’’The people of India deeply love you, and all that you have done to bring our two countries closer to each other”.