THE pocket calculators must be overheating at the Office for National Statistics.

In April, the people who provide our facts and figures worked out that the number of employees on zero-hours contracts had increased by 174% between the autumn of 2005 and the last quarter of 2012. No doubt this counted as productivity, of a sort.

It meant that instead of 73,000 individuals being forced to drop everything when an employer whistled, with no guarantee of work, sick pay, holidays or other fripperies, 200,000 were as flexible as any gangmaster could wish. Young people were commendably willing. The number of 18 to 24-year-olds aspiring to zero had gone up by fully 262%.

Last week, the ONS went back to the abacus. The national serfdom index was reviewed. Had they said 200,000? It seems there was a slight methodological mishap. As though rewriting Gogol's Dead Souls for the 21st century, the statisticians added another 50,000, just like that, to their estimate.

Even while struggling to keep up there was a certain lack of conviction from the ONS. For one thing, they harboured the suspicion that many people stuck on zero hours don't know what a zero-hours contract is. These days labourers think it's just work, normal, a part of life, even - as the Victorians might have said - their lot. Certain employers would dearly like that to be true.

As ever, our royals lead the way in the great national adventure. There are 350 summer employees at the beck and call of a Buckingham Palace subsidiary. They work on demand or go unpaid as Monarchy Inc sees fit. Should they wish to take on second jobs, these toilers for the richest family in the land must obtain written permission. In effect, they are temporary bonded labour, trapped in the worst of both worlds.

If they don't like it, they can work for the Tate galleries, for the Cineworld movie chain or for Sports Direct, where 20,000 staff stay fit and flexible, running to keep up with the demands of modern retail. Failing that, the zero-hours workers will find themselves serving some socially responsible enterprise that forgot to ask tricky moral questions when it outsourced its canteens or its cleaning.

The exploitation fad has caught on quickly. Councils with policies to cover every ethical conundrum see no problems with zero-hours contracts. Universities, where the young discover idealism, are shifting lecturers to earn-as-you-teach as fast as they can. By the admission of its own human resources department - a comedy title, these days - 27% of Edinburgh's staff are on zero-hours contracts. According to the EIS at Napier, 30% of lecturers are so indentured. Some probably teach social policy.

The ONS observers have revised their numbers upwards in the certain knowledge that every estimate will turn out to be laughable. The blight is spreading too quickly to be measured accurately. Even the Government, an administration with a keen interest in parting workers from their rights, has conceded that there are 307,000 folk in the social-care sector in England alone who are on zero hours.

If that's one baseline, millions of jobs are at issue. A study published by the Resolution Foundation in June, part-based on the ONS Labour Force Survey - and therefore on the old figures - found that "health and social work" accounted for 20% of zero-hours contracts. Hospitality was 19%, administration 12%, retail 11% and "the arts, entertainment and leisure" 8%. The rest were mopped up by education, public administration, manufacturing, transport and "technical".

So if - a cautious if - 20% is equivalent to 307,000 jobs in England alone, somewhere between one-and-a-half and two million individuals are involved. I doubt that's the whole story. One of the supposed mysteries of Britain's banker-induced economic coma, after all, has been the apparent resilience of employment. Predictions of mass joblessness have been unfounded. Economists have been more baffled than usual.

It doesn't seem complicated now. Zero hours explains why the figures for those "in work" have remained tolerably high. The phenomenon also helps us to understand why, in survey after survey, those who are otherwise gainfully employed complain that they need more hours. As the Resolution Foundation report, A Matter Of Time: The Rise Of Zero-hours Contracts, explains "those employed on such contracts work fewer hours on average (21 hours per week) than those who are not (32 hours per week)".

You could complain, of course, and pray that the boss doesn't feel vindictive when next he is handing out shifts. That's if he doesn't sack you with neither explanation nor compensation. That's if he is even slightly interested in your need for proof of earnings to rent a flat, get a credit card or open a bank account. That's if he even pretends to care about your childcare problems or other family commitments.

Those who defend zero-hours contracts claim they suit some people. No doubt there are a few who don't mind waiting all day for the phone to ring for the sake of a few minimum-wage hours. Employers meanwhile enthuse over flexibility, even when that virtue seems only to apply to one party in the deal. Strangely enough, though, those who impose zero-hours arrangements are never on such contracts themselves. Why not?

Money might have something to do with it. As the Resolution Foundation also explains, "those employed on zero-hours contracts receive lower gross weekly pay (an average of £236 per week) compared to those who are not (an average of £482 per week). This is, in part, a consequence of working fewer hours on average per week but ... the gross hourly wages of those employed on zero-hours contracts (an average of £9 per hour) are lower than those who are not (an average of £15 per hour)".

Even before the ONS revised its figures, the graph for these contracts was easy to plot. It began to climb, and to climb steadily, in 2010. Previous recessions had not produced these grotesque abuses. As with the assault on social security, the bankers' debacle was the perfect excuse for the shredding both of wage rates and rights.

The idea, old as the Tory Party, is to create a low-paid and permanently insecure workforce that will do as it is bid, when it is bid. That this does the economy no good whatever, at least in terms of consumer spending, has become a minor detail. Zero-hours contracts are vindictive by design. This, for the Coalition and its friends, is your future while you work on into old age with a pitiful pension.

In a blog written in May, Ian Brinkley of the Work Foundation looked at the 2012 Skills and Employment Survey. He called it "sobering reading". The report found that one in four workers was afraid of unemployment. In the circumstances, that made sense. What bothered Brinkley more was that "roughly the same percentage were anxious about unfair treatment; and between 30% and 40 % were anxious about changes in job status - such as less say, less skill use, less pay or less interesting work".

A brave new world? There used to be a name for working people reduced to obedience, deference, dependence and fear. They used to call them peasants.