The English grammar school system has widened the gulf between rich and poor, according to a new study.

Researchers from the University of Bristol, the University of Bath and the University of London’s Institute of Education studied the pay of more than 2,500 people born between 1961 and 1983. They found the gap between the highest- and lowest-paid was bigger in areas with grammar schools than those which had a comprehensive system.

The difference in hourly pay between the best- and worst-paid stood at £16.41 in selective schooling areas between 2009 and 2012, compared to just £12.33 in those with comprehensive secondaries, according to the academics.

The highest earners educated in grammar school areas also received the largest pay packets, earning an average of £1.31 per hour more than their counterparts from comparable comprehensive authorities.

Even allowing for other social factors such as gender, ethnicity and occupational class, the researchers found that 18 per cent of the income gap between the highest and lowest earners could be explained by the school system.

Research leader Simon Burgess said schools with high-ability pupils were more likely to attract better teachers. “Selective schooling systems sort pupils based on their ability and schools with high ability pupils are more likely to attract and retain high quality teaching staff,” he added. “This puts pupils who miss out on a grammar school place at an immediate disadvantage. In addition they will be part of lower ability peer groups, which also affects their chances of succeeding at school.”

A report published last year by the Sutton Trust found that grammars educate a disproportionate number of children from private prep schools. They should work harder to encourage children from poor backgrounds to apply, it added.

Earlier this month, however, TES revealed that more than half of grammar schools were set to fundamentally reform their admissions by giving preference to bright children eligible for free school meals.