Children in care are being failed by the education system, with fewer than one in 16 leaving school with five or more good GCSEs - rising to one in 25 in Wales, according to official figures.
They show the governments in Cardiff and London are not delivering on promises to close the gap between the achievement of children in care and their peers.
Factors contributing to their poor performance, say children's charities, are negative attitudes towards such children by schools, a lack of priority given to education by the care system, and the problems faced by the children.
More than half of the 7,500 children who leave care in England each year leave school without passing a single GCSE or equivalent vocational qualification. That compares to 96 per cent of all English pupils getting at least one GCSE, and 55 per cent passing five or more exams at grades A*-C.
In Wales, only 37 per cent of 397 young care leavers aged 16-plus had passed at least one GCSE by March 31 this year, compared to 93 per cent of all Welsh Year 11 pupils in 2004.
Only 4 per cent managed five good passes, compared to a Welsh average of 51 per cent.
Peter Clarke, the children's commissioner, said: "I'm shocked and disappointed. We have known for ages that this is a key area where we need to do better.
"Research has shown that corporate parents have lower expectations of children in their care. We need to do normal things, like checking on a child's attendance.
"There are some authorities pursuing parents to the point of imprisonment over non-attendance when the record of their looked-after children is appalling."
The situation has worsened in Wales since last year. In England, the situation has not improved in the past three years despite the Westminster Government's target of increasing the proportion of children in care gaining five or more A*-C GCSEs by 4 percentage points each year.
Promises of official action followed a 1999 TES campaign which showed that two-thirds of councils did not know what children in their care had achieved in national tests and two-fifths had no idea about their GCSE results.
Although there were initial improvements, the latest figures have prompted The TES to relaunch its campaign today and urge both governments to take further action.
An Assembly government spokesperson said it currently had no all-Wales targets for the education qualifications of looked-after children. Instead, it agrees local targets with each local authority as part of policy agreements.
But she said there had been a 10 per cent improvement in the proportion of looked-after children aged 16-plus leaving school with at least one qualification between 2002 and 2004, to 40 per cent.
"The Assembly recognises that the education attainment levels for looked-after children remain lower than their peer group and, with its partners, is developing improvements through schemes such as the Children First programme," she added.
A report published in September by the children's charity NCH called for the Government to pledge to end the differences in achievement between looked-after children and their peers by 2020. It revealed that fewer than 100 children in care go to university each year.
Katie Morris went into care at the age of nine after the death of her mother. This summer she graduated from Manchester Metropolitan university with a degree in politics and sociology.
She said she was lucky that she found foster parents willing to fight her corner. She had always tried to keep her personal circumstances secret from teachers.
"As soon as you say you are in care, people stigmatise you. Some people seem to think that a child is in care because they have done something wrong."
Last month Sir Cyril Taylor, chairman of the Specialist Schools and Academies Trust, said the state boarding sector could be a cost-effective way of providing for children in care.