A staggering £50million plus could be required to replace a secondary school in Ramsey which is no longer fit for purpose.

Part of Abbey College's grounds could be sold for housing development to help fund the scheme, Cambridgeshire County Council members will hear tomorrow (Tuesday), but there are no guarantees that all the £6.3million estimated as income from the sale would go back into local education.

Even the cheapest option would cost more than £19million in interest charges.

Responsibility for the maintenance of the accommodation and site at the college rests with the trust which runs it and the Education Skills Funding Agency (ESFA).

The county council's children and young people's committee is being recommended to support the trust by sharing a feasibility study and condition survey with EFSA with the aim of securing funding to enable the trust to address the college's condition issues and to maximise the use of its accommodation.

Three options for replacing the school, identified in a feasibility study drawn up for the council, will be discussed by the committee on September 10.

They are a new build to the north of the present site at a cost of £53.66 million, a new build to the south at the location of existing buildings for £55.83 million and the refurbishment of the existing school, plus any new buildings required at a cost of £47.24 million. All three options would have costs offset by the sale of land and each could be expanded to 10 forms of entry.

A report to the committee said: "The feasibility commissioned by the council has demonstrated that in spite of the potential receipt from land sales for residential development, all options...would require a huge amount of additional capital investment.

"The council is not in a position to be able to consider funding schemes of this magnitude, especially given that the cost would need to be met from prudential borrowing."

The report added: "While borrowing costs vary depending on interest rates and scheme length, we could expect borrowing £48million (Option 2, the least costly) over a three year period to result in costs of approximately £19.2million."

The council owns a playing field at the school which could be sold for housing development, but the site is shown as being allocated for education use in Huntingdonshire District Council's local plan, which guides development and was only approved in May this year. There would have to be discussions between the two councils to see if a change of use would be acceptable.

A number of landowners are also involved.

Abbey College opened in 2006 following the amalgamation of the former Abbey and Ailwyn schools. It has a capacity of nearly 2,000 pupils, but has reduced admission numbers because of falling demand.

However, pupil numbers in the area are expected to increase and it is expected that pressure for places will also go up at other schools, such as St Ivo in St Ives, where parents send children as an alternative to Abbey College.

A spokesman for the county council said: "The Abbey College Trust has been considering options for the future delivery of secondary education in the town and the best use of the site and buildings available for some time, and are committed to work in partnership with the council to identify and secure a long-term solution.

"A feasibility study, commissioned by the council working closely with the school, the district council and local county councillors, explored a number of options to improve the condition of the school, including rebuilding on the existing college site, refurbishing existing buildings or constructing a new offsite school campus."

The spokesman added: "In spite of the potential to sell some land on the school site to build houses, all options would require a huge amount of additional capital investment. Given the limited financial options available to the school and the severe financial constraints of the council, the recommendation to the committee is that we support the school by sharing the feasibility and condition survey with the Education Skills Funding Agency (ESFA) with a view to securing funding."