THE head of all-boys Sandbach School says the town's whole secondary education system is in jeopardy as all-girls Sandbach High School forges ahead with plans to admit boys.
Peter Wiles warns he will go on a counter-attack and enrol girls if that happens.
The row comes after talks between the headteachers of the town's two single-sex schools broke down. Sandbach High head John Leigh has applied to Cheshire Admissions Forum to enrol boys aged 16 to 18.
Mr Wiles spoke of his plans to fight back at a Sandbach Town Council meeting on Thursday.
He said: 'If we lose 10 boys to the other school, that is £30,000, which means we would have to lose a member of staff.
'If the plans go ahead to take boys into their sixth form, then we will be having big adverts in the papers the next day saying 'girls are being admitted starting Monday'. We could start taking girls tomorrow.'
Under the current rules, Sandbach School can admit up to 25% of girls to its sixth form.
But Mr Wiles fears the changes could result in GCSE pupils sucked into mixed learning. Government tables show consistently better results at GCSE in single-sex schools.
He said: 'This is an added concern. A logical progression would be for the girls' school to seek permission to enrol 14 to 16-year-old boys.'
However, Mr Wiles says it is not too late for a reconciliation - branding the potential split a 'waste of resources which should be spent on children's education.'
He says he is backed by the Local Education Authority, Learning and Skills Council and a large group of parents from both schools who want to see an end to the feud.
A Cheshire County Council spokesman said it, and the Learning Skills Council, are in favour of working together. She claimed: 'This will secure the best outcome for learners.'
Sandbach High head Mr Leigh refused to comment this week.
Cheshire Admissions Forum will decide next month whether to allow boys to enrol at the girls' school.