Average life expectancy for women in the Mid Sussex district could be approaching 90 by 2030 a new study has found.
Men are also set to live longer than official estimates predict as the historic gender gap narrows.
But life span differences between better and worse off communities are likely to increase to levels that mirror those dividing Western and developing countries, say the researchers.
The study, based on Office for National Statistics data combined with advanced mathematical modelling, suggests that average life expectancy in the Mid Sussex district for women will rise from 85.54 in 2015 to 88.97 in 2030.
For men, it is predicted to increase from 82.9 to 87.98 over the same period.
But the upward trend masks significant regional differences, the research shows.
By 2030, people in affluent southern England and well-off districts of London are expected to be living more than eight years longer than those in northern urban centres such as Blackpool, Liverpool and Manchester, as well as South Wales.
That is equivalent to the difference in life expectancy between the UK and Sri Lanka or Vietnam.
Within London, a stark survival gap was seen between the haves and have-nots. In 2012, the wealthy residents of Kensington and Chelsea lived on average five or six years longer than their poorer neighbours in Barking, Dagenham and Tower Hamlets.