Prison Service Union or PSU is a British Trades Union that
represents rank and file prison officers. The Prison Officers Association is the TUC
affiliated union that covers much the same ground but is opposed to privatised prisons, if
only because private operators pay less than the government, and refuses to have anything to
do with them. The PSU therefore tends to represent staff employed in these privately
opearates prisons and therefore has the reputation of being a moderate union.