Not only have those at the bottom of the pile been forced to put up with a widening pay gap, they have also suffered the "double blow" of extreme anxiety over their employment prospects.
In a study to be published in the new year, Brendan Burchell of the Cambridge Faculty of Social and Political Sciences warns of the dangerous effects of this "polarisation" of the labour market on society. He has calculated that manual workers are 60 per cent more likely to move into insecure jobs than professionals.
The paper, "The Unequal Distribution of Job Insecurity", also points out that employment insecurity causes severe psychological problems, marital breakdowns and reduces life expectancy.
Mr Burchell, whose research is to be published in the International Review of Applied Economics, contends that there is no evidence to support the New Right's view that insecurity boosts workers' motivation. While a degree of concern about one's future may help productivity, real job insecurity has a negative impact on the output of most people, Mr Burchell argues.
And employees rarely "get used" to such stress. The effects become cumulatively worse as the years wear on. Insecurity feeds on itself, so that those who have experienced a period of unemployment enter a downward spiral, finding it more difficult to establish themselves in permanent jobs, partly through the negative attitudes of employers towards the jobless.
The paper points to a "stark break" between the relatively secure Sixties and Seventies and the labour market after 1979. In the Eighties there was a far higher risk of moving from secure to insecure employment. That was partly due to a deep recession which saw unemployment rise to levels more than three times as high as anything that had been experienced since the war.
Mr Burchell contends some of the insecurity was the responsibility of the Conservative Government, which introduced legislation to make it easier for employers to dismiss their workers.
The study reports the existence of "Survivor Syndrome" among those left after redundancies. Among the survivors, researchers have found decreased motivation, morale, confidence and loyalty, and increased stress, anger and bitterness.
Peter Hain, Labour's employment spokesman, said the research proved his party's argument that deregulation of the market was a dangerous policy. "It doesn't produce greater efficiency and it has bred job insecurity which is not only bad for health, it also makes people less efficient and less likely to have the confidence to innovate," he said.
He continued: "It is clear there was a sea change in 1979 when the Conservatives came to power. Job insecurity is partly the result of global competition, but it was made far worse by the manic deregulation pushed through by the Tories stripping workers of their rights.
"It left people incredibly vulnerable. This research shows that life for many people - particularly those at the bottom of the pile - is poor, nasty, brutish and short."Reuse content