Take two schools in the deprived heart of Sheffield - home town of former education secretary David Blunkett who insists that good schools in such areas put others to shame. But just because a good school is in a deprived area does not mean that its pupils are deprived as anyone who examines the facts behind Mr Blunkett's argument will soon realise.
Serving Sheffield's Manor ward, the fifth most deprived containing a school in England, is Waltheof school, a 1,000-pupil mixed 11-16 comprehensive.
Almost half of its pupils (48 per cent) get free school meals, an underestimate of their poverty, says head Andy Gardiner, since parents of Year 10 and 11 students see no point in registering for free meals when children buy chips at lunchtime anyway.
Waltheof sits among older housing; 20 per cent of pupils are from ethnic minorities, mainly Asian; the rest are working-class white, and, after generations of unemployment, cynical about the value of education.
Nevertheless, the school ranks in the Government list of the 200 most improved schools, having lifted its proportion of pupils getting five Cs or better at GCSE from 9 to 22 per cent in the past five years. Judged against schools with similar free-meal levels it is also well up among the cluster of "standard" comprehensive schools.
But if you were to judge Waltheof against its nearest neighbour, you would have to tell a different story.
For down the road in Park Ward, surrounded by grim housing estates, is Sheffield's All Saints' Catholic high school, a mixed 11-18 specialist sports college. Its GCSE score is much better than Waltheof's: 51 per cent of pupils got five good grades last year. Why is it doing so much better? One look at its free-meals figure will tell you.
Despite its deprived location, just 11.8 per cent - less even than the national secondary average of 14.9 per cent - qualify for free school meals.
The discrepancy between area and intake can be explained by the school's admission criteria: closeness to the school is last on the list. Entrance to All Saints' depends on a recommendation from a Catholic priest.
The school does not interview, but, because there are only two Catholic schools in the area, it takes pupils from as far away as Barnsley. If it exhausts the supply of Catholics, it will offer places to other Christian denominations. Only then will it take those who live nearby.
All Saints does not pretend to face the same task as Waltheof, says deputy head Clare Scott: "Our critical mass of supported youngsters makes it easier to deal with everybody".
But nor does Waltheof give up in the face of deprivation, says Mr Gardiner:
"We believe we can be better. But you can't all be the best, and it's not helpful when comparisons are made with schools in very different contexts from ours."