New diplomas for 14 to 19-year-olds will fail as long as they are forced to compete with traditional A levels and GCSEs, which will continue to be favoured by middle-class parents, teaching leaders said yesterday.

The new diplomas have been hailed by the Government as the most significant educational reform in 40 years. Combining practical skills, work placements and classroom learning, they are designed to end the centuries-old divide between academic and vocational and will be available in 17 subjects.

The Association of School and College Leaders (ASCL) said yesterday that teenagers and their parents would be reluctant to make the leap of faith required to sign up to the new qualifications, which are untested.

John Dunford, the general secretary of the ASCL, said that the diplomas had been made so complicated that many pupils and parents simply did not understand them.

“People aren’t going to go for something that they don’t understand,” Dr Dunford said at the ASCL annual conference in Brighton yesterday.

“The fear is that the take-up will not be as high as we or the Government would like it to be for the diplomas, particularly in the early years.”

The Government had originally intended to offer diplomas in 17 subjects at four levels of difficulty: foundation, higher, progression and advanced. Yesterday it announced more difficult “extended” versions of the foundation, higher and advanced diplomas – increasing the number of possible permutations for new qualifications from 51 to 119.

Enthusiasm for the diplomas among pupils and parents will become apparent in the next two months as 14 to 16-year-old students decide whether to go for diplomas when they become available in September, or whether to stick with GCSEs, A levels and other existing vocational qualifications.

Early indications suggest that some schools and colleges involved with the first round of diplomas have had to withdraw them in some subjects because they expect a low take-up.

Jane Lees, the head teacher of Hindley Community High School Arts College in Wigan, Lancashire, said that some schools were wary of offering the diplomas, regarding them as one leap of faith too far.

Because individual schools and colleges will not be able to offer the full range of diplomas by themselves, pupils will have to travel between institutions for different classes. In a town such as Wigan, which had “horrific” traffic congestion, this would be problematic, Ms Lees said.

Malcolm Trobe, the head teacher of Malmesbury School in Wiltshire and a member of the Government’s expert advisory group on diplomas, said that schools were finding it difficult to recruit staff to teach the diplomas “because a lot of the . . . detail of the diplomas is actually quite late coming through”. Dr Dunford said that schools needed to know whether A levels would be scrapped in favour of diplomas, a decision the Government has said it will not take until 2013.

He called on ministers to bring existing A levels and GCSEs into the diploma system so that all pupils study for a “general diploma”. This would boost the status and take-up of diplomas and spell the end of GCSEs and A levels as free-standing qualifications.

The first five diplomas taught in England from September will be in construction, engineering, IT, health and creative and media. More than 800 schools and 150 colleges will offer them to a potential 40,000 pupils.

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