We have had this for the last 4 years, but it was taken away this term. It was for all primary schools in the district and all children, not just Yr3 and under. The government praised the local council as it was all part of a healthy eating campaign (long before the Jamie Oliver stuff), so the council logically took that as their cue to stop
Only problem now for parents is that it hits you hard when they suddenly start charging again.
Also, our take-up on school meals has dropped through the floor so the kitchen staff are talking of strike action because of cut hours/job losses.