FURIOUS parents will hold a demonstration over changes to grammar school admissions outside County Hall this week.

The group will not be able to speak at the children's services scrutiny committee on Thursday, despite asking to be represented, because committee chairman Brenda Jennings said the agenda was already full.

A year ago, 19 children in Denham and Gerrards Cross were not given grammar school places at first, because their catchment schools Dr Challoner's Grammar School, in Amersham and the Royal Grammar School in High Wycombe were already full and other children lived closer.

The latest changes, which would come into effect in September 2007, are designed to sort this, but now parents say their children will miss out because pupils in Gerrards Cross and Denham would get preference at the two Dr Challoner's schools.

Debbie Robertson, from Great Missenden, has a son at Dr Challoner's and is leader of the Fair Admissions Action Group. She said if proposals had been in place for next September, 14 Gerrards Cross and Denham children would have been given places at the Dr Challoner's schools at the expense of Prestwood and Lee Common pupils.

Aylesbury MP David Lidington said county council officers had told him the problem for Gerrards Cross children was a one-off.

He said: "The county council is trying to put right one injustice to people in Gerrards Cross by creating another; this time for parents in Prestwood and Great Missenden.

"In that case, why press ahead with these changes which are causing so much dismay and uncertainty to my constituents?"

Public consultation ends this week and Cllr Marion Clayton, Buckinghamshire County Council's cabinet member for schools, will make the final decision on April 16. She said parents had made their feelings clear and there was nothing to demonstrate against. But Mrs Robertson said: "It is really important to show that we are not accepting any change, which is so inherently unfair, without a fight."

Nick Powley, the council's head of policy, performance and planning, agreed last year's problems were caused by a bulge in numbers of 11-year-olds and the next bulge was not likely until 2010. Even so, one or two children might find themselves without a grammar school place, he said.

Chiltern district councillor Mimi Harker whose son has been given a place at Dr Challoner's, said changes would push out boys on the fringes of the school's catchment area. She said places should be allocated on the results of the 11-plus score.

Missenden and Prestwood county councillor Mike Colston has presented a petition objecting to the plans to county council chairman Margaret Aston.