By Ian Dunt

The rate of social mobility in the UK is now slower than during the medieval ages, according to new research.

Researchers at the University of California found that it takes longer for a family's economic and social status to change since the industrial revolution than it did during earlier periods of human history.

"The huge social resources spent on publicly provided education and health have seemingly created no gains in the rate of social mobility," said professor Gregory Clark.

"The modern meritocracy is no better at achieving social mobility than the medieval oligarchy. Instead that rate seems to be a constant of social physics, beyond the control of social engineering."

Academics traced the fortunes of people with a rare surname - one rich, the other poor - from 1858-87 to now.

The holders of the 'rich' surname are still "substantially wealthier" in 2011, four generations later, than the holders of the 'poor' surname.

They also lived an average of three years longer - a good indicator of socio-economic status.

The researchers found that at the current rate of convergence, the groups would not be equal until another two to four generations had passed.

That contrasts negatively with the convergence of groups much earlier in British history.

From the Domesday Book in 1086 until recently, academics found that English society showed "complete long-run social mobility", meaning there were no permanent classes of rich or poor.

Those bearing the name 'Smith', for example, are mainly descended from the simple village blacksmiths of England in 1350.

By 1450, three or four generations later, the share of 'Smiths' at Oxford equalled their share in the general population. By 1650 there were as many 'Smiths' in the top one per cent of wealth holders as in the general population, indicating that that groups had been fully absorbed into the elite.