Last year it appeared that a Cheshire boys’ school and a neighbouring girls’ school were heading for a fairytale ending to a 20-year quest to achieve a joint sixth form.

The plan was for pupils to have the option to take A-level courses at either school. But relations soured when the girls’ school announced that it wanted its sixth form to go co-ed from September next year, sparking fears that it would poach pupils from the boys’ school.

Peter Wiles, headteacher at Sandbach school, an independent boys’ school where pupil fees are paid by Cheshire council, said: “If 10 boys go to the girls’ school, the money goes with them, I will have to make a member of staff redundant. It is inevitable that we will have to take girls in the sixth form and compete with the girls’ school. We don’t think the competition will be healthy. But what do we do when one party wants to collaborate and the other doesn’t?”

John Leigh, headteacher at Sandbach high, a 1,300-pupil girls’

comprehensive, was unrepentant: “Why does the head not have faith in his own school? It is a big vote of no confidence if he cannot convince his pupils to stay with him after five years.”

The two schools had been so close to clinching the deal to collaborate a year ago that 30 Sandbach school boys chose courses at the girls’ school.

But talks broke down last February because the girls’ school had reservations over the timetabling of the lunch hour and how the joint sixth form would be led.

Mr Leigh, headteacher since 1993, said he was fed up with the protracted talks.

“I am frustrated with the process. It has been going on for 20 years and we have made no progress whatsoever. Something has to change. Why should a boy who wants to do Spanish, A2 media and law - subjects the boys’ school does not offer - not be able to come to my school?”

Over the past year, meetings have been held between the Learning and Skills Council, Cheshire local education authority and Sandbach high to resolve the situation.

A Cheshire spokesman said: “Both this authority and the LSC believed that Sandbach high should reconsider its proposal in order to reduce any element of competition between itself and Sandbach school.”

A spokeswoman for the LSC said: “We would prefer the schools to work collaboratively.”

Last year 78 per cent of Sandbach high’s girls and 64 per cent of Sandbach school’s boys got 5 or more A* - C at GCSE. At Sandbach high, 41 per cent of A-level entries were A or B grade, while at Sandbach it was 41.4 per cent, including one AVCE exam.

In a 2004 report, inspectors described Sandbach school as “very good”, and whose pupils and parents held it in high regard. The Office for Standards in Education said in 2000 that the girls’ school was high achieving and successful.

Anne Stawpert, whose son is in Year 11 at Sandbach school and whose daughter is in Year 13 at Sandbach high, said: “My concern is that if the schools do not collaborate, there is a risk they will lose students to other sixth-form colleges. And if the sixth forms at the two schools get too small, they will have to get rid of them. This will damage education in Sandbach.”

The Independent Cheshire Admissions Panel will consider Sandbach high’s application to open 60 of its 240 sixth form places to boys on February 22.

The panel’s recommendation will then be considered by the council.