School bosses and parents are opposing an attempt by the Church of England to impose its identity on one of the most successful grammar schools in the country.
They are resisting what they see as a "hostile takeover" and want it to remain multi-faith.
However, diocese bosses believe the Blue Coat School in Liverpool should have been designated a Church of England (CofE) school, based on historical documents.
The Diocese of Liverpool says it has no intention of changing the school ethos.
It has asked the Department for Education and Skills (DfES) to clarify the position of the school and whether it should be designated as a Church of England school.
In 1998, Blue Coat was classified as a non-CofE school - but the diocese believes its founding charter is evidence that it should be otherwise.
Head teacher Sandy Tittershill was meeting with the school's lawyers on Wednesday to discuss their opposition.
He said: "I have been here for more than 40 years and no one during that time has ever suggested to me that this, at any time, was a Church of England school.
"This has been a school for everybody - we are a multi-faith, multi denominational school. We are very content, very dynamic and we're very successful and also very popular - and we wish to remain as we are.
"We have received about 700 letters so far in support of the Blue Coat School maintaining its current status and only five in support of the Church of England."
In 2005, 98 per cent of pupils at the school, in Wavertree, achieved at least five A* to C GCSEs.
School bosses fear that its admissions policy could be affected if the Church of England is successful.
But the diocese said it would have no control over admissions, and maintained it would be a matter entirely for the governors.
"If it were designated as a Church of England school we would simply aim to support the governors and staff as they continue their work," a spokesman said.
"This is certainly not an attempt to take over the running of the school or to control admissions," he added.
A public meeting will be held at the school on 8 January, and will respond to the DfES by 9 February.
