Take home pay is gross earnings minus income tax and national insurance contributions. For families the figures therefore exclude family allowances—for years up to 1976–77—and child benefit—from 1977–78. The calculations of tax however, show the tax deducted from earnings, including tax on family allowance and family allowance deduction—"clawback"—where appropriate.

For years up to and including 1969–70 average earnings are the Department of Employment's estimates of the average weekly earnings of full-time male manual workers in October of each year. For later years to 1976–77 the figures are based on the average of hte New Earnings Survey estimates of the average earnings of similar workers in April at the start and finish of each income tax year. based on the average of the New Earnings Survey estimate has been updated to October 1977 by the monthly index of average earnings, and for 1978–79 an estimate for May 1978 has been used, obtained by updating in line with movements in the new series of the monthly index of average earnings.

For years prior to 1975–76 it has been assumed that the employee was not contrated out of the graduated pension scheme.

The figures for married couples with children are affected by the transition from child tax allowances and family allowances to tax free child benefits starting in 1977–78.

These figures seem to accurately record take-home pay, after deducting rent, but make no allowance for rent rebates and also other benefits, as follows:

For an average rent of £6·30 the weekly spending power rises to £43·32, as shown in the answer.

The figures for the man on £58 per week with a rent of £16 per week cannot be reconciled so easily. The corresponding figures to those above are:

For an average rent of £6·30 the weekly spending power rises to £46·38 as shown in the answer.