By Tom Warren
BBC News, England
England's north-south wealth divide is at its highest level for more than 30 years, the BBC's Changing UK report has found.
The study, commissioned to look at neighbourhoods across the UK, reveals "dramatic changes" in the distribution of wealth from 1970 to the current decade.
Researchers from the University of Sheffield divided households into three categories - "asset wealthy", "non-poor non-wealthy" and "breadline poor".
They found, using data from a number of sources, there is a "clear north-south divide" in England which is becoming sharper.
Professor Danny Dorling, who led the research team, believes the "divide" now runs from the Severn Estuary in a diagonal line to the Humber Estuary.
Cities including Lincoln and Leicester are now in the South, Professor Dorling claims.
He said in Lincolnshire it was partly the retirement of southerners moving there, to places like Gainsborough, Boston, Grantham and Lincoln, which meant it had entered the South.
"It stops dead as soon as you get northern-looking industrial terraces.
"There's this psychological barrier people have about moving north from the South which hasn't decreased - if anything it's increased."
He said a huge decline in manufacturing in the 1990s had led more people to move south to find work, or had discouraged people from moving north.
Barbara and Mark James moved from Middlesbrough to Romsey, Hampshire, for employment reasons in 2006.
Before Teesside, they had lived with their two daughters in Blackburn for 16 years.
Barbara James's family moved south for work reasons
Mr James, 47, is a research chemist while his wife works in a finance department at a sixth form college.
Mrs James, 48, said: "Most of the big chemical companies are in the South. He [her husband] used to work at ICI in Manchester, it doesn't exist any more.
"But with house prices and the amount of traffic down here I would happily go back [to the North]."
Professor Dorling said a town or city's train time to London now had a direct impact on its economic success, partly due to the increasing importance of London's financial sector.
All BBC local radio station areas with the highest number of breadline poor households are in the North, according to the researchers.
In England they are Newcastle, Merseyside and the West Midlands.
Southern Counties and Oxford have the most asset wealthy households.
But London stood out as having high numbers in both categories, with relatively few in the middle.
The study shows that just five areas of England - Newcastle, Tees, Merseyside, Manchester and Sheffield - saw their populations shrink between 1981 and 2006.
Cambridgeshire had the biggest rise over the same period, with 28% growth.
"Within England the greatest increase in population in the South has actually been along the borders of the South running in a line from the tip of Cornwall to the Norfolk coast.
"This sharpens the north-south divide," the report said.
The researchers used Census data from all UK households and other statistics to put together the report, which was aimed at finding out how the UK has changed since the 1960s.