If there was no link why would we spend umpteen billion pounds a year giving children the best education that politicians deem the country can afford? But in fact the new LSE study does break new ground. Until now, sceptics have been able to point to the generous funding in some authorities - and countries - and say it doesn't "buy" better results.
That's why some people would like any new national funding formula (see article opposite) to be as parsimonious as possible. The LSE report makes that argument less tenable, but the researchers now need to tell us how the extra money makes a difference. Do lower class sizes yield better "returns" than a full library, for example?
Furthermore, any comprehensive cost-benefit analysis of education spending would have to consider more than just GCSE results and future incomes. Education can also improve social cohesion and quality of life, but how can you ever quantify that accurately in numbers and percentages?