A family of four needs an income of at least £23,000 sterling a year to maintain a comfortable lifestyle, according to new British research.

A lone parent with two children is also shown to need more than £20,000 to live in comparable circumstances, taking account of child-care costs and tax, even if the family has no car. A single man of working age, running a car and renting a bedsit, would need just £11,800. Whereas the analysis says a lone parent with two children aged 10 and four needs weekly earnings of at least £385 to live comfortably, income support benefit pays £98.70 plus housing costs.

The figures for "modest-butadequate" incomes have been calculated by the family budget unit at King's College, London, in a modern adaption of the technique pioneered by welfare pioneer Seebohm Rowntree in York in 1901. He costed all the items a family would need to support itself.

Using prices in York in 1997, the unit has constructed budgets for each of eight different household types as both tenants and owner-occupiers - 16 budgets in all.

Items included in the budgets range from toilet paper (£1.33 a week for a family of four) to Christmas decorations and fireworks (62p a week). An annual holiday is costed, as in most cases is a second-hand car.

The modest-but-adequate budgets are defined as sufficient to eat healthily, but providing a better diet than people living on benefits could afford.

For a single man of working age, running a car and renting a housing association bedsit, the budget is put at £11,800 a year. For a married couple without children, renting a one-bedroom council flat and running a car, it is £15,100.

A couple with two children aged 10 and four, renting a three-bedroom council house and running a car, would need £23,100 sterling; a similar couple buying their own home, a three-bedroom semi-detached, would need £24,250.