"The Pensions Policy Institute, an independent research charity, puts average public sector salaries at £25,600 and those in the private sector at £25,300, although the PPI says salaries soared in the private sector when it came to the very top jobs."
That is a debateable point - I've seen other research which says that for the MOD (and presumably the wider public sector), 50% of staff earn under 20K per year, and 75% of staff earn under 24K per year. There are opportunities for decent pay in the public sector, but they are few and far between outside of London.
Of course 99% of statistics can be made up on the spot :-)