Daniel O’Neill is a bright, ambitious 15-year-old who sits for his GCSEs next year. Normally, he would expect to transfer with his friends to take A-levels at Peter Symonds in Winchester, one of the largest sixth form colleges in the country and rated “outstanding” on just about every count by Office for Standards in Education.

Though he would like to move with his peers, Daniel has been paying attention to the debate over the future of A-levels and the growing interest in the International Baccalaureate (IB) diploma, which provides an alternative.

Despite the excellent reputation of Peter Symonds, he is attracted to Taunton’s, a less prestigious college in Southampton but one of the few places locally offering the IB Diploma, which he thinks might give him an edge in the competition for university places. “Which one should I go for?” he asks. “I’m unsure which type of course is going to help me in applying to university.” Daniel hopes to apply to Ivy League universities in the US and has been told that they might look more favourably on the diploma.

It’s a dilemma being faced by sixth formers as more schools either switch to the diploma or run it alongside A-level courses. There are 93 state and independent schools and colleges in the UK registered to teach the diploma. Others, such as The Perse School for Girls in Cambridge, are preparing to introduce it.

The IB diploma is a wide-ranging course involving the study of six subjects over two years. These include the home language, a foreign language, maths, science, humanities and the arts, plus a compulsory core of an extended essay, a course in theory of knowledge and a section called “creativity, action, service” (for Taunton students, this meant helping build a school in Tanzania).

The conventional wisdom until recently was that the intellectual demands of the IB and A-levels were broadly similar. Dissatisfaction with the British government’s Curriculum 2000 reform of A-level, however, has led some schools, such as King’s College School, Wimbledon and the North London Collegiate to move over to the diploma.

The IB’s metamorphosis into an elite qualification was given a further boost last summer when the Universities and Colleges Admissions Service awarded it a tariff worth up to six A-grade A-levels. Universities were told that a score of 38, the average achieved every year by more than 200 pupils at Sevenoaks, one of the first independent schools to adopt the exam, was deemed to be equivalent to five As at A-level. A score of 28 on the Diploma, four above the failure level, is equivalent to three grade As.

Paula Holloway, the principal of St Clare’s in Oxford, which has been teaching the IB for nearly 30 years, says it is valued by university admissions tutors in Britain and abroad. “The IB is a broad-based, rigorous course of study which, unlike A-level, has not been subject to grade inflation,” she says.

But some schools resisting the change accuse supporters of the diploma of denigrating the A-level as a marketing tool to promote the IB. Richard Russell, the headmaster of Colfe’s, a school in south-east London, says A-levels allows students to make choices “which they find immensely liberating after the straitjacket of GCSEs”.

Neil Hopkins, principal of Peter Symonds College, says it is untrue that A-levels give a narrow education. Many of his students take five AS subjects in the first year and four A2s in the second, plus AS-levels in critical thinking and general studies. They also get involved in a range of extra-curricular activities, from Duke of Edinburgh Awards to ballroom dancing.

Does the IB give students such as Daniel an advantage when applying to Ivy League institutions? Anthony Nemecek, director of the Education Advisory Service of the US-UK Fulbright Commission, which helps students applying to American universities, says not. All but the smallest US universities understand and appreciate the A-level, he says, and they also take into account the reputation of the school attended and the reference it submits for the student.