Long before he was identified as a nuclear weapon-toting scourge of the middle classes, Les Ebdon risked the wrath of a less politically sensitive group: ageing academics.

Speaking to Times ÖйúAƬ in 2009, the vice-chancellor of the University of Bedfordshire said that researchers could be past their prime by the tender age of 30.

"The fact is that many researchers produce their best work early on in their career," he said. "Einstein is the classic example, but it is true of nearly everybody."

Professor Ebdon is not the first to have highlighted this trend, but how does academia compare with other professions?

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In a paper published in the journal Science in 2010, researchers used high-tech data-mining techniques to assess, among other things, fame. Looking at individuals with Wikipedia entries who were born between 1800 and 1950, they concluded that the median age at which people become famous had fallen from 42 in the early 1800s to 34 in 1864 and 29 by 1950.

It is worth adding that the study also found that this average varied significantly by profession, with actors achieving fame much earlier than writers and politicians.

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As far as academia is concerned, there are many reasons why groundbreaking discoveries may be made disproportionately by younger researchers. These may be as intangible as the arrogance and ambition of youth or as unremarkable as simply being in the lab when older colleagues are diverted by other duties.

But will the tradition of Young Turks making waves continue? This week we report on a study by the ÖйúAƬ Funding Council for England, which says that the proportion of academics aged under 30 at English universities has declined from 14 per cent in 1995-96 to 8 per cent in 2010-11. Meanwhile, the proportion of over-60s has risen four percentage points to 9 per cent.

In the sciences this may be partly down to changing career structures, but the jobs crisis facing early-career researchers does seem to be worsening, and the figures suggest an element of bed-blocking is at play.

Of course, it would be crazy to write off the talents of older academics. Speaking in 2001, the chemist Alan Battersby said it was no coincidence that he had won his greatest plaudits (including US accolade the Robert A. Welch Award) for work carried out five years after his official retirement in 1992.

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"There is no doubt that I was far more able to concentrate on research once the load of administration was taken off me," he said.

But following changes to the default retirement age, and with the recession and the funding squeeze putting strict limits on expenditure, there are worries that an increasingly tight tourniquet is cutting off the flow of fresh blood to the sector.

This is a nuanced and thorny issue, but academia has plenty of those: perhaps it is time for the sector to grasp the nettle and set up a panel with representatives from all career levels to thoroughly interrogate the problem.

If our universities send young talent elsewhere - whether to jobs in industry or more welcoming institutions overseas - they will not only miss out on those productive early years: they could also severely damage the sector's long-term health.

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john.gill@tsleducation.com.