Six children have been denied places at Hertsmere Jewish Primary School's nursery this autumn after the local council miscalculated the distance of their homes from the school.
The heavily oversubscribed HJPS gives priority for its 60 nursery places firstly to those with siblings at the school and, next, to those living closest to it, according to measurements by Hertfordshire County Council.
But the council admitted this week that it had got the calculations wrong in some cases.
One upset mother whose child remains on the waiting list said: "People who shouldn't have been offered a place were given one ahead of those who should have been offered one, but weren't."
Another in a similar situation said there would be "an almighty scandal" if matters were not rectified. "We believe friends of ours were offered a place who live further away than we do."
Whereas many councils measure geographical proximity to a school by drawing a straight line from the home, Hertfordshire determines it by the shortest possible route.
A council spokeswoman explained: "In this instance we used one route which, on investigation, was found not to be suitable for inclusion as a shortest designated route and we hadn't used a route which was suitable. Sometimes routes do change - because fences are moved or they become overgrown or for a variety of reasons - and we aren't always made aware of this unless someone points it out."
She added: "We think that six children have been affected by this situation and we are working closely with the school to resolve it." She was unable to say whether they would be offered places. The council is switching to a straight-line system of measurement next year.
Another worry for parents is that if their children miss out on a place at nursery this year, they will fail to get into the HJPS reception class in 2011, as priority is given to those who have attended the nursery.
But Becky Hilsenrath, the HJPS governor responsible for admissions, said the school had written to reassure the parents of the six children.
"If they apply for reception in 2011, we will deem them to have been in the nursery and give them equal priority to children who were actually in the nursery in 2010.
"We will have to take an extra six children in reception next year. We're hoping that Hertfordshire will be able to provide us with extra resources."
The school had passed responsibility for calculating distances to the council several years ago to comply with the new statutory admissions code. "When we were informed of the mistakes, the governing body was extremely concerned.
"We have had exhaustive conversations both internally and with Hertfordshire Council on an urgent basis. We recognise that parents have been caused a lot of distress."
Heavy demand for HJPS has led some parents to consider sending their children to Ilford Jewish Primary School, which is 20-plus miles away.