One in nine British adults have no qualifications, an analysis of official figures suggests.
A new study reveals wide differences in the educational achievements of adults across the country.
In some areas, as many as a third of 16 to 64-year-olds lack any qualifications, while in others the proportion is as low as 2%.
The University and College Union (UCU), which conducted the analysis, warned the figures show Britain is divided into "the haves and the have nots".
The study is based on an analysis of Office for National Statistics (ONS) figures showing the proportions of adults of working age (16-64) with no qualifications in 2010.
The findings show 11.3% of British adults do not have any qualifications. In England, this figure is 11.1%, in Wales it is 13.3% and in Scotland 12.3%.
UCU analysed the qualification rates for 632 parliamentary constituencies in England, Scotland and Wales.
It found that in constituencies such as Glasgow North East and Birmingham Hodge Hill more than a third of adults of working age have no qualifications (35.3% and 33.3% respectively), while at the other end of the scale, just 1.9% of adults in Brent North lack any qualifications, while in Romsey and Southampton North the figure is 2.3%.
UCU said that people in areas with the lowest levels of qualifications were likely to suffer most from Government policies which the union says will restrict access to education. These include the Government's plans to triple tuition fees, and scrapping the education maintenance allowance (EMA) - a grant handed to the poorest teenagers to help them stay in education.
A spokesman for the Department for Business, Innovation and Skills (BIS) said: "The Government is committed to ensuring everyone gets the education and skills they need to find work and get on in life, and that young people who have left school without basic literacy and numeracy get free lessons."