At least a dozen British towns and cities will have no single ethnic group in a majority within the next 30 years. Leicester will become the first 'super-diverse' city in 2020, then Birmingham in 2024, followed by Slough and Luton, according to a new study of population trends in the UK.

The report reveals that Leicester has seen the proportion of its white population fall from 70.1 per cent in 1991 to 59.5 per cent today. By 2016 the white population will make up 52.2 per cent of the population, falling to 44.5 per cent by 2026. 'Britain is becoming ever more plural; our diversity ever more diverse,' said Danny Dorling, professor of human geography at the University of Sheffield, whose predictions are based on the most comprehensive study into the country's population trends. 'This increased diversity is most evident in its cities, with plurality becoming commonplace.'

The immigrant and ethnic populations are no longer characterised by large, well organised Afro-Caribbean and South Asian communities, said Dorling. Instead, increasing numbers come from countries scattered across the globe - from Germany to Guyana, from Sweden to Singapore.

'It is going to become increasingly difficult to generalise about Britain's plurality because different cities are experiencing different levels and types of diversity,' he said. 'This creates a complex challenge for those responsible for successfully managing the country's changing population.'

In the Thirties, the proportion of people living in Britain who were born in foreign countries was 2.5 per cent. Typically these individuals came from one of 15 countries, in particular Ireland and India. Today more than 10 per cent of the population were born abroad, with no single ethnic group dominating.

Sukhvinder Stubbs, chief executive of the Barrow Cadbury Trust, which commissioned Dorling's research, said the findings indicate key challenges facing Britain, including a need to reframe the immigration debate and to focus on the changing pressure on the country's resources. 'For Britain's major urban centres, ethnic diversity is the reality,' she said. 'Regardless of future immigration patterns, it is just a matter of time until cities such as Birmingham become plural. Even if we prohibited another single soul from entering the country, the trends have already laid root.'

In the period from 1991 to 2026, which will see Leicester's white population fall from 70.1 per cent to 44.5 per cent, the city's second largest ethnic group, Indians, is predicted to rise from 22.9 per cent to 26 per cent. The Pakistani population will triple to 3.3 per cent, while the proportion of Africans will rise from 0.4 per cent in 1991 to 11.2 per cent.

Birmingham's transition to plural city status will, however, be markedly different to Leicester's, added Dorling. The proportion of white people in its population will fall from 77 per cent to 47.7 per cent. But while much of Leicester's growth in ethnic minorities will be driven by African growth, Birmingham's population shift will be dominated by those of Pakistani descent.

Dorling's research also looks at the shifts in population patterns in towns that are not expected to become plural in the foreseeable future. Oldham, for example, will remain a town with an overwhelmingly white population. However, it will witness a significant change in its demographic profile, with the town's white population falling from more than 90 per cent to 74.4 per cent in the 30 years from 1991.

'Contrary to popular opinion, Oldham's ethnic minority population is not homogeneous,' said Dorling. 'The town's second largest ethnic group after whites is Pakistani, but by 2021 there are likely to be as many Bangladeshis in Oldham as there are Pakistanis.'

Dorling's research also shows that, although Greater London's population is already significantly diverse with a white population of 67.5 per cent, it is not likely to become plural in the near future. By 2026 the white population is predicted to reach 60.7 per cent, with just eight of London's 33 local authority areas predicted to become plural.