According to the Unemployment Unit, a pressure group which has charted all the changes, the real number of jobless people is more than 4.1 million, instead of the official figure of more than 3 million. The unit says this represents 14.2 per cent of the population instead of the Government's figure of 10.6 per cent.
It claims the Government's statistics, which define unemployment as the number of people claiming unemployment-related benefits, miss out 1,168,600 people who would have been classed as unemployed if the Government's definition had remained the same as in 1982. Many of those missing are 16 and 17-year-olds, sick and disabled people and single parents, older men, married women and people who are disqualified from claiming Income Support, or do not claim.
Some economists say the unit's figures are an overestimate and that a more accurate picture of unemployment in Britain is provided by the Employment Department's Labour Force Survey. Its latest figures, for summer 1992, showed the number of unemployed was 2.76 million - 95,000 more than the Government's figure for that period.
The Labour Force Survey's figure is based on an international definition of unemployment from the International Labour Organisation (ILO) of people who have sought work in the previous four weeks and are available to start work the following week.
However, Paul Convery, a researcher at the Unemployment Unit, said the ILO's definition imposed a stringent test which excluded many people who were out of work. 'We are not saying that there are 4.1 million people who are ready to start work straight away and who have sought work within the last four weeks. There are many disincentives to people who receive benefit seeking full- time work, because of the benefits trap. And during a recession people are discouraged from constantly seeking work.'
The unit's calculations are based partly on a monthly survey of population data and partly on the number of people missing from the official count as a result of each change in the system, adjusted to make allowances for people no longer unemployed.
The unit says the official unemployment figure is only 129,000 short of the last post-war record high of 3,124,000, in July 1986, and predicts it will pass that figure in May. The figures also show notified vacancies have fallen after two months of slight increase - from 109,100 to 104,700.