We had this problem at our village school. Worst offenders were the local nursery groups who have the kids from when Mum goes to work at 8am and they drop the children by mini bus at 0855 and then collect them all again at 3.30.
I took our village bobby along, in my car, to watch the performance. Following day he came along again in my car, got out, put his helmet on and booked the bloody lot of them. He also got three of the nursery busses for out of date tax, two for no insurance and four for no seat belts on the children.
One driver, who told him to f*** off, he arrested on the spot for obstructing a police officer and called up the area car to take her to the nick. Turned out she didn't even have a licence. 6 months community service, a 2 year ban and a hefty fine. She no longer works for the nursery.
We don't have so much of a problem any more.