Schools will be encouraged to do more to push their most able pupils to achieve A* grades under a new GCSE performance indicator being promoted through the Specialist Schools and Academies Trust.
The measure, developed by Professor David Jesson, an associate director of the trust, focuses on the percentage of pupils gaining three or more AA* grades rather than the proportion achieving five or more A*-Cs.
He said it would particularly help schools with large proportions of pupils who achieved among the top 40 per cent key stage 2 national test scores in the country.
"Almost all of them (the top pupils) get five A*-Cs, so in a way that indicator is pretty redundant and no longer makes sense," Professor Jesson said.
"It seems to me that where you have almost 100 per cent on five A*-Cs you need to provide schools with a new challenge of what might be good outcomes for their pupils.
"This is to encourage schools to give as much attention to As and A*s as they have done in the past to A*-Cs."
The York University academic said he presented his findings to hundreds of schools at the Specialist Schools and Academies Trust conference in Birmingham last autumn and received a very positive reaction from headteachers.
The trust, which represents the vast majority of England's secondary schools, is considering highlighting the idea in its annual report next month.
Professor Jesson's analysis of last year's GCSE results shows that 97 per cent of pupils who came in the top fifth of their cohort for KS2 test scores at primary school, achieved at least five A*-C GCSEs.
Among the next fifth down, 85 per cent achieved the benchmark.
But there could be wide variation in the number of top GCSE grades between schools where pupils had achieved the same standards as 11-year-olds.
He gave an example of two secondaries where pupils had gained an average of 27 points in their KS2 national tests. But in the first school only 20 per cent of the same pupils scored at least one A* or A grade at GCSE, whereas in the second 47 per cent managed it.
Professor Jesson has produced statistics that allow schools to compare themselves against the latest national averages and, based on KS2 scores, work out the percentages of pupils that should be gaining A and A* GCSEs.
He said the framework would help schools ensure they were doing all they could with the top 40 per cent of pupils in the country. Asked whether this was elitist, Dr Jesson, said: "Nothing I am saying is mitigating against helping pupils at the lowest end of the spectrum.
"The greatest improvements we have seen have come from schools helping lower ability pupils. But some schools have got to a point where it is difficult to progress any further on that measure."
The academic also rejected the idea that his work simply replicated the concept of contextual value- added (CVA) by working out what pupils ought to achieve based on their previous performance.
"CVA only categorises schools into one of three groups - whether they are doing better than expected, as expected or worse than expected," he said.
"Trying to rank schools on their CVA numbers is a nonsense. This is a new indicator that looks at pupils across the board, shows how they are doing and offers a challenge for schools to do more."