By Angela Harrison
BBC education reporter
Xavier Gordon-Brown found the maths GCSE "easy" at the age of seven
More than 600,000 students in England, Wales and Northern Ireland will receive their GCSE results later on Thursday.
It is likely grades will increase since last year, when more than a fifth of entries were awarded an A or A*.
For the first time there will be a number of results for England's new Diploma qualification, designed to mix academic with work-related study.
Ministers expect the number of schools targeted for poor performance to fall to 280, from 631 two years ago.
Schools in England targeted under what is called the "National Challenge" are those where fewer than 30% of pupils achieve five or more good GCSE passes (A* to C) including maths and English.
In January, when the league tables for England based on last year's exam results were published, 440 schools were in this category.
The government says in 1997, a total of 1,600 schools were in this category - about half of schools - and that now one in 10 is.
The results of the GCSEs taken by students in England, Wales and Northern Ireland this year will be released by the Joint Council for Qualifications, which represents the exam boards.
Students in Scotland received the results of their Standard and Higher grade exams earlier this month.
And many pupils in Northern Ireland have already received some of their GCSE results because two thirds of exams taken there were set and marked by the local board, the CCEA. Those results were released last Tuesday.
Among the youngest people to gain an A* grade in maths was Xavier Gordon-Brown, seven, who now feels qualified to offer his prime ministerial namesake some advice.
The gifted youngster, from Haywards Heath, West Sussex, declared: "I was pretty confident, the GCSE was easy."
While many twice his age will be celebrating their results, thousands more will have fallen short of the grades they need to continue in education.
George Turnbull of Ofqual, the new exam regulator in England, believes young people who get disappointing grades are getting forgotten in the debate about whether exams are getting easier.
He said: "You don't see that side of it in the newspapers and I think there's rather too much emphasis put on the rise in grades.
"Every time the overall results go up there are cries of 'dumbing down'. It's a lot of nonsense, the children work harder than ever they did for their exams.
"It's the students who don't quite make it, these are the ones who are going to have the problems. And these are the ones who need our help."
In the autumn, about 11,500 students began England's new Diploma courses - seen as making the biggest change to England's secondary school system for a generation.
The qualifications are being brought in gradually in England until 2013.
On Thursday, results will only be available for a limited number of those taking the Foundation and Higher levels.
The highest level of Diploma, advanced, which is equivalent to three and a half A-levels, will be awarded from next year.
Those getting their results are among the first to have been educated entirely under a Labour government.
Schools Minister Vernon Coaker said "I look forward to congratulating pupils, teachers and parents on their hard work later this morning. I remember the anxious wait from when I was a teacher. Most will have got the grades they need to progress to the next level whether that is A levels, Diplomas or work based training such as an apprenticeship.
"But if young people have not got the grades they wanted or were expecting they should not panic. There are more options than ever for young people finishing their GCSEs and no one should think they have nowhere to go."
Under the government's "September Guarantee", all 16 and 17-year-olds have the right to a suitable course or training place, including an opportunity to gain qualifications they may have missed out on the first time round.
League tables for England based on official results will not be published until next January.