This week London’s half a million Indians celebrate Diwali, the Festival of Lights, in a pensive mood. For sure, there is a lot for them to be positive about. The data from the Government’s race disparity audit last week showed how British Indians, far from being a disadvantaged minority, rank top for earnings and educational attainment. Yet there is an air of anxiety hanging over the community too. British Indians are not immune from the existential angst pervading the country at large, as reflected in a recent Ipsos poll showing that 72 per cent of Britons feel the country is off on the wrong track.

In many respects, the Indian diaspora has lived the ultimate British Dream. In common with many immigrant communities, Britain has provided them with somewhere to build a new life and secure better prospects for their families. Indian parents have worked long hours and made sacrifices so that their children can enjoy a better future.

The majority came to these shores as refugees or economic migrants and have, almost universally, prospered in a single generation. Migrants, as a group, are people who are prepared to uproot themselves, who want to improve their lives. In Britain they found a generous-spirited nation that welcomed new talent, applauded personal responsibility and rewarded wealth creation. These were opportunities not always found in their home countries, and successive Prime Ministers from Thatcher to Blair and Cameron spoke to their aspiration.

One of the most eye-catching data points from the new Cabinet Office website of Ethnicity Facts and Figures is a breakdown of household income, revealing that 35 per cent of British Indians earn £1,000 or more a week compared to a national average of 24 per cent in the same top income bracket. The Indian diaspora has also invested heavily in education and the results are evident here too. Department of Education rankings show that Indian pupils, alongside Chinese, have the highest attainment throughout school, make the most progress and are the most likely to stay in education and go to university.

But the Indian influence goes well beyond monetary measurement or educational league tables. Large swathes of London, from Southall to Wembley and Upton Park, and now even Mayfair, have benefited from the entrepreneurial drive of the Indian community. The strong family business ethos has spurred urban regeneration, reviving countless high streets and business parks across the capital — not forgetting the massive cultural contribution to food, music, cinema, dance and fashion, all of which is being marked throughout 2017 by the UK-India Year of Culture, launched by the Queen at Buckingham Palace earlier this year.

So with all these achievements, what’s the gripe? The restiveness comes from doubts about Britain’s commitment to remaining an open, tolerant and welcoming nation after Brexit and the prospect of a return to the politics of envy, where aspiration and wealth creation are punished, not rewarded.

Many Indians came to Britain via sub-Saharan Africa, where they often experienced the trauma and humiliation of being forced out of their adopted countries because of their ethnicity and local envy about their economic success. For some in the older generation there is a fear, however irrational, of history repeating itself. For others, the changes to the non-domicile tax regime has forced their hand, prompting some ultra-high-net-worth Indian families to move offshore to the likes of Monaco, Dubai or Singapore. For most, though, the concern is more basic. Having laid down their roots and been exemplary in their efforts to integrate into society, British Indians are questioning whether the dream of progress between the generations can still be delivered.

British Indians are questioning whether the dream of progress between the generations can still be delivered Lord Gadhia

Behind this sentiment is a very large exposure to the fortunes of the City — with 32 per cent of Indians working in professional industries, compared with an average of 20 per cent across the population. Financial and professional services, which are driven by meritocracy, have provided a massive engine for social mobility. If, however, the Brexit negotiations fail to secure the right deal for continued trade in services, it would be a major setback for British Indians.

Equally important, British Indians see themselves as a “Living Bridge”, to use the words of Indian Prime Minister Narendra Modi, between the world’s largest democracy and the world’s oldest. India is the second-largest investor in the UK after the United States and has invested more in Britain than in the rest of Europe combined. London is the natural gateway for Indian companies to access the EU single market and without providing that crucial entry-point the risk is that future investment flows will become more dispersed. This is a time to harness, not alienate, a globally connected community which can be of ever greater value as we forge new relationships with the rest of the world.

There are not just economic anxieties at play here but social ones too. As the first generation grows older and requires greater provision of health and social care, there is a wariness about relying on the state, which often provides services insensitive to the community’s cultural needs. Indians have a proud history of self-reliance that has minimised their call on public services, but hard-working professionals also need help looking after their elderly parents. Other communities who manifestly pay as much in taxes would have demanded more back from the state but Indians are not inclined to beg for help. Having made a disproportionate contribution to the Exchequer, they deserve proper support and dignity in their old age.

At its heart, the unsettled feeling among the Indian diaspora is a concern about who now speaks for them. Diwali is a festive reminder that good ultimately triumphs over evil, knowledge wins over ignorance and hope prevails over despair. This year many will be hoping that the “Light” they celebrate will illuminate the path to renewed confidence in the British Dream.

Jitesh Gadhia is a Conservative peer