A recent report by Swansea University showed that in the public sector workers are actually paid 2% less than in the private sector. You need to fully job evaluate jobs in both sectors to properly compare. If you do this you see massive pay advantages in the private sector and especially in manufacturing.
Remember it is a fiction that the public sector are paid more.
UNISON National officer Gavin Edwards from the "Bargaining and Support unit" detailed what they can do to help branches and stewards. You can get background information and local reports on private sector bidders for public contracts and find out what has gone wrong with these contractors elsewhere. Email the unit and you will get a report back also they have access to the IDS pay data base so you can compare and contrast pay rates.