Only 5,096 of the 142,311 school pupils who took A-levels or equivalent in Year 13 this summer were eligible for free meals. That is 3.5 per cent of entrants and compares with 16 per cent at key stage 2.
The figures, released in an annual Government analysis, show that moves to make education or training compulsory for all 16- to 18-year-olds would have to tackle entrenched class characteristics.
Of those disadvantaged pupils who took GCSEs, 21.1 per cent got five A-star to C grades, including English and maths. This was a slight improvement on last year's figure of 19.5 per cent and an increase in line with national trends, but well below the average of 45.4 per cent.
The proportion of pupils entitled to free school means who went on to do A-levels or equivalent in school was just 7 per cent, meaning disadvantaged pupils either drop out of education or head for sixth form or further education colleges.
The figures also show that the GCSE results of most minority groups are improving faster than their white British counterparts.
Lord Adonis, schools minister, said: "This is another year of GCSE success for minority ethnic pupils."
But the Conservatives criticised the large gap between children who get free school meals and the rest.