Richmond Inclusive Schools Campaign (Risc) is taking Richmond Council to court over the long-running argument about plans for a voluntary aided Catholic secondary school.

In February, Risc wrote to the council saying it believed the way the proposals for the Clifden Road site were being handled was not compliant with the new Education Act.

Under the act, a council that thinks it needs a new school must first seek proposals for an academy or free school, where there is a limit of 50 per cent faith-based admissions.

Risc is now taking the issue to a judicial review with help from British Humanist Association (BHA), after the council refused to alter its plans for the new school in Twickenham – stating that it and the Diocese of Westminster were acting within the law.

The Diocese of Westminster said: “The proposed court case being brought by Risc and the British Humanist Association, a national organisation that campaigns against the existence of all schools with a religious character, seeks to use procedural arguments to prevent an entirely legitimate proposal to increase the educational choices available for parents and children in Richmond.”

Risc spokesman Jeremy Rodell said he believed the council and the Catholic Diocese were playing the system to secure the most exclusive type of Catholic secondary school possible.

He said: “It has become increasingly clear that the council has no intention of changing its plans, whatever the outcome of its recent consultation.

“Only a legal challenge will make any difference, but Risc does not have the resources to mount one. So we very much welcome the BHA’s involvement.”

BHA chief executive Andrew Copson said: “We have seen repeatedly how religious providers largely avoid competition when establishing state-funded schools, and instead make arrangements directly with local authorities to open schools without local people being offered any alternative.

“These approaches to local authorities have always been successful. If the practice is not challenged, we face a future of discriminatory state-funded religious schools being opened without the same rules applying to them as to inclusive schools.”

A council spokesman said: “The council has not yet taken decisions in respect of the diocese proposal, or in respect of the use of the site in Twickenham and, therefore, any judicial review challenge would be premature.”