man reading
© Luke MacGregor / Reuters
A quarter of British adults have literacy levels so low they would struggle to read a bus timetable, new research has found.

Government figures indicate some 28 percent of UK adults are at literacy level 1 or below, the equivalent to GCSE grades of D to G. A pass grade for GCSE level is considered to be a C or above.

Research by the Joseph Rowntree Foundation (JRF) found 5 million adults lack basic reading, writing and numeracy skills deemed necessary to carry out a job.

England is among the worst performing countries in the OECD, with roughly one in 20 adults found to have the literacy and numeracy levels of a five-year-old.

It is also the only nation in the OECD where the average literacy score for 16- to 18-year-olds is lower than 55- to 65-year-olds.

In other developed nations, young people tend to have much higher literacy and numeracy scores than their older counterparts, but in Britain the opposite trend is occurring.

Some 23 percent of 16- to 18-year-olds are at literacy level 1 or below, while the same figure is 19 percent for the older age group.

The same pattern extends to numeracy, where 29 percent of 16- to 18-year-olds are level 1 or below, compared to 26 percent of 55- to 65-year-olds.

"In a prosperous country like Britain, everyone should have the basic skills they need to participate in society and build a career," said JRF Head of Policy Katie Schmuecker.

"But these shocking figures show millions of adults are being left behind in the modern economy, holding back their potential and the productivity of our businesses suffering as a result."

In-depth analysis by the OECD published in January found literacy rates among young people to be among the lowest in the developed world.

The organization ranked English teenagers aged 16 to 19 the worst of 23 developed nations in literacy and 22 out of 23 in numeracy.

The report, based on 2012 data, found England was better off investing its money in basic education rather than trying to broaden access to university.

England has three times as many low-skilled 16- to 19-year-olds as top-performing countries such as Finland, Japan, South Korea and the Netherlands.