The figures are taken from page 25 of the Institute of Fiscal Studies report on UK inequality (pdf).
Just to note, the only reason Major's figures are not much worse is that his period is overshadowed by the serious recession of the early nineties where growth in everyone's earnings were hit - the gap between rich and poor was contracted due to the recession. It is much more difficult to reduce inequality during a period of growth.
2.8% p.a growth in earnings over 10 years amounts to around £300bn extra, of which the poorest quintile would have received around £50bn. The extra Labour spending over 10 years on the NHS, education, public transport, social services and tax credits, new deal etc - which disproportionately helps the poorest quintile, amounts to around £1000bn. So we can see how those on the lowest wages have easily been helped by over £100bn.