Academic argues in new book that society has the widest divide since the days of slavery

London is most unequal city in the developed world, with the richest tenth of the population amassing 273 times the wealth owned by the bottom tenth – which creates a "means chasm" not seen since the days of a "slave owning society", according to a new book.

In Injustice: Why Social Inequality Persists published by Policy Press, Danny Dorling, a professor of human geography at Sheffield University and an expert on social disparity, paints a bleak picture of an extremely unjust Britain where differences in wealth have led to a profoundly divided society.

Dorling said Labour had managed to stop the gap in incomes from getting bigger, but this had not stopped the rich getting richer. The wealthiest had amassed assets such as second homes and expansive stock portfolios.

He says the government's latest figures show that in the capital the top 10% of society had on average a wealth of £933,563 compared to the meagre £3,420 of the poorest 10% – a wealth multiple of 273.

"Other comparable cities like New York, Stockholm, Sydney ... have wealthy people, but not as many wealthy people as London," said Dorling. "There is an inbuilt bias towards inequality in UK society today.

"We are getting wealth inequalities in London now as far as we know that have not been seen since the days of a slave-owning elite. The lesson is that it is not enough to just stop the disparity in incomes from getting bigger – you have to make it smaller to stop wealth inequality from getting worse."

This wealth gap has produced an alarming health gap – with the life expectancy at birth of the richest group rising by a year annually, while the poorest are seeing almost no rise at all. In 2008, a female born in London's exclusive Kensington and Chelsea could expect to live until 88 and nine months – a year earlier she would have reached 87.9. In Glasgow, by contrast, where women were expected to live until 77.1 in 2007, the rise was only a month to 77.2 in 2008.

"You have rich people living longer and longer, while life expectancy has all but stalled for the poor," says Dorling.

In Europe, only Portugal appears more unequal than Britain. Instead of seeking to reduce inequalities, Dorling argues, Westminster politicians simply accept that it is unfortunate but inevitable, rather than seeing it as undoing the "warp and weft of society".

The result is that the affluent have been allowed to lose touch with the everyday norms of society. The academic points out the cost of a flat in the City of London rose by 24% to almost £450,000 in 2009.

"Prices jumped at a time of recession. The rich really aren't like us ... they operate in a different world," said Dorling.

This segregating effect means that the wealthiest are "socially excluding themselves by choice".

"[The rich] are no longer even thinking of sending their children to the same schools as others, nor having holidays that in any way resembled the norm, nor having salaries that bore any resemblance to national averages, nor relying on the same health services as others ... as far as we can tell, at no other time had so many people in countries like the United Kingdom not felt part of the societies there," he said.

The effect on politics has been the dramatic "super concentrating" of the Conservative vote in a series of wealthy constituencies in areas such as the south- east. By 2005, one in six Tory voters would have to shift from some of the most Conservative seats to other party strongholds to spread the Tory vote equally across the country.

Dorling says this "geographical polarisation in underlying beliefs is where David Cameron finds his party". In the past, this feature of Conservative voters, combined with large now inequalities, has led to a "decade of political instability".

"The last time the Tory vote was so geographically concentrated was when we had a similarly unequal society in 1918. The result was a decade of instability, with a coalition government between the Liberals and the Conservatives. It means this election is about real choices."