India's hunger for the English language is manifested in the names of its schools. In Jaipur, the chief city of Rajasthan, under the letter B alone you can find the Blue Bells school, the Blue Birds school and the Bo-Peep school. Some don't sound so salubrious: the address of the Modern Happy school is listed as "Behind Petrol Pump, Gapalpura Model Tank Road". Many of them are likely to have been inspired more by profit than by educational ideals, their innocent nursery names disguising black-hearted entrepreneurs making a quick buck from Hindi-speaking parents who are anxious to promote their children into better jobs via familiarity with the world's most powerful language. It is easy to imagine an Indian variant of the kind of school satirised by Dickens and Waugh - schools born out of similar middle-class ambitions - in which a poorly-paid Miss Gupta chants the class through Wordsworth's Daffodils while dreaming in their inward eye of a couch in Bollywood rather than Windermere.

The one I visited in Jaipur last month, however, seemed a model of commitment. This was the Step by Step school, one of a chain of fee-paying English-schools in north India, and I'd been invited to talk to the pupils about "journalism, your life, those kinds of things".

It was nine o'clock on a Saturday morning. A group of senior pupils aged about 16 sat cross-legged in neat rows, girls to the left and boys to the right, all in blue uniform. They remained completely silent through our on-stage conversation. Their questions, when they came at the end, were sharp and well-framed. Other memories of those 45 minutes are now a blur, save for two moments. One came when my hostess invited me to talk about nationalism and, perhaps a little too late, I realised I was being asked to proclaim its virtues rather than find fault with it as a political philosophy; "national integration" has always been an important project in a country of so many languages and creeds but the Mumbai attacks have installed a patriotic fervour against Pakistan of a kind Britain hasn't known since pictures of HMS Nelson were hung from the walls of Orwellian crammers.

The second arrived when in some headmaster-like spasm I talked to the audience about their future. They were a fortunate generation, I said. India and China were the new world powers, and India may in the end hold the advantage over its rival because of India's expressiveness in the English language, its democratic and more flexible governance and its long historical relationship with the west. "You're lucky," I said. "You were born at the right time in the right place. Seize the chance."

"I especially appreciated those remarks," a teacher said later. "It was good that you said them." In fact, they may have been said rather jealously. That morning online I'd read the widely quoted remarks of the investor Jim Rogers, who made his original fortune in currency speculation when he founded the Quantum fund with George Soros. "I would urge you to sell any sterling you might have," Rogers said. "It's finished. I hate to say it, but I would not put any money into the UK."

Alone in an Indian hotel room, aware of a bill that would show how the pound's value to the rupee had sunk over the past few months by 20%, it was perhaps too easy to feel depressed. Then again, all of Britain is depressed: a well of melancholy. In this week's Guardian, Max Hastings wrote the most chilling prognosis for a country softened and made greedy by decades of financial illusion, now facing a future of impoverishment and civil unrest. British workers would keep their wages "only if they perform skilled tasks which others cannot, or provide their services for substantially smaller real rewards than they have received in the past". The education system was a mess, producing young people "fit only to be global losers" when by contrast "anyone who has met young Chinese and Indians of the new generation perceives their tigerish hunger, as well as their skills".

The last is true. Out of Step by Step, Bo-Peep - and for all I know the Modern Happy school, squatting behind the petrol pump - a different kind of Indian is emerging equipped with the individual aspiration traditionally associated with America, minus the brashness. Thirty years ago, when I first went to India, such people were rare and drawn either from the trading communities or the narrow seam known as the Anglophone elite. Now the middle-class has hugely expanded and believes rightly in its technical competence. If the age of territorial empires were to return in a process of reverse colonisation, Indians would be as perfectly or imperfectly equipped to run Yorkshire as the Britons in the Indian civil service once governed Bengal. As they may one day be happy to do, because the problems for India (and China) in the long term make those of Britain in the medium term look like molehills.

There was a time when I thought I would be happy to live, perhaps even die, in India. This may have been foolish romanticism, but it was easier then to ignore all the statistics in UN development reports; social inequality aside, their impact was located in the distant future. That future is much closer. Twice as many people live in India now as when I first saw it. By 2030, it will overtake China as the world's most populous country: between four and five times as many people as the United States now has, packed into a land only a third as large.

Those figures in themselves will bring intolerable pressure on the things we consider vital to a decent life - on land, water, crops and pleasure. Add the predicted effects of climate change, and the future of India and China as stable nations looks doubtful. The permanent snow cover on the Himalayas may not last beyond 2050; the Ganges, which provides 500 million people with water, draws more than two-thirds of its summer flow from the Himalayan meltwater that the snow and glaciers will no longer be there to supply. Then, of course, there is the likely influx of several million refugees from Bangladesh due to a rise in sea level.

All things considered, I was probably wrong to tell my Jaipur audience how lucky they were. Nowhere on earth, not even middle-class India, is this the ideal age to be born. The economic depression will do its worst. Britain may emerge as little more than a destination for educational and cultural tourists (pockets of violence are a danger, but so were brigands for gentleman making the "Grand Tour"). But the much graver threat of unsustainable consumption and climate change will still tower over the world, and Britain may be a better place than many to face them. There will be copious water in the north and more root vegetables. In the long term, taking into account the Keynesian dismissal of that perspective ("we're all dead"), our grandchildren will stand a better chance here than by the dry bed of the Ganges. This offers one remote reason, admittedly an insular and inhumane one, to be cheerful.