Although the government last year estimated the number of people on zero-hours contracts to be about 250,000 (weekly LELR 331), a survey last week by the Office for National Statistics put the figure at nearly one and a half million.

Its survey of 5,000 businesses from January to February this year found 1.4 million employee contracts that did not guarantee a minimum number of hours. The previous estimate - from the Labour Force Survey - put the figure at almost 600,000 for the period from October to December 2013.

Part of the problem in working out the numbers is that there is no legal definition of zero-hours contracts, so different groups measure them in different ways, and have different perceptions of what should be included.

Section 2 of the Government’s consultation on zero-hours contracts stated: “In general terms, a zero-hours contract is an employment contract in which an employer does not guarantee the individual any work and the individual is not obliged to accept any work offered”. So even though different definitions are used, the common factor is a lack of a guaranteed minimum number of hours of work.

The ONS therefore decided to use this as its definition, which includes zero-hours contracts as well as some other contract types that do not guarantee a minimum number of hours.

Looking at the types of people employed on zero-hours contracts, the Labour Force Survey showed that they were more likely to be women, in full-time education or in young (16-24) or older (65 and over) age groups, perhaps reflecting a tendency to combine flexible working with education or working beyond state retirement age.

Nearly two thirds of people employed on zero-hours contracts work part-time compared with around a quarter of people not employed on them. On average, someone on a zero-hours contract usually works 25 hours a week compared with 37 hours a week for people not employed on them. Just over a third of those employed on a zero-hours contract want more hours, with most wanting them in their current job.

The government consultation which looked at whether employers are abusing zero hours contracts closed in mid-March and a response is awaited.

Iain Birrell at Thompsons Solicitors said: “Some of the media misunderstood these differing figures as showing a rise in the use of zero hour contracts, but this is not the case. What it does show though is that there are different ways to measure their numbers, and this in turn will cause problems for a sensible debate about them, and argument over their numbers will be used to distract from argument about their effects.

Whether the UK will continue to have Europe’s least regulated labour market in two years remains to be seen, but it is already clear that getting reliable data about this aspect of it will be like nailing jelly to a wall.”