The funding gap between state and private secondary pupils has grown by 20 per cent in three years. When Gordon Brown announced his objective to lift state spending on children to the private sector average in his 2006 Budget, the average bill for a private school day place was £8,150, while spending in state schools was £4,750 per pupil.
Since then, the gap has increased from £3,400 to £4,446, with the Independent Schools Council (ISC) putting the average annual fee for day pupils at £10,296 in 2008/09 compared to the £5,850 spent on each pupil in a state school.
And the gap has grown by more than 50 per cent since 2002 to almost £4,500 a child, according to ISC figures. In 2002, private schools were charging an average £6,550 compared to the state school spend of £3,650 - a gap of £2,900.
The pledge was always likely to prove undeliverable for the simple reason that private schools only stay in business by spending more on education than state schools can afford. If that meant that they became unaffordable for some and the number of private schools fell, then so be it, but so long as private schools remain affordable for some, they will continue to exist.
Which is why government ministers have changed their tune and now say that Mr Brown's 2006 goal was to bring state spending up to the then private-sector average of £8,150, which of course it wasn't, but that is history and there is no more money in the pot.