The grant-maintained school chosen by the Labour leader Tony Blair for his son Euan is embroiled in fresh controversy after being told by the Government it cannot use interviews to select a new intake of seven-year-old choir boys.

Gillian Shephard, the Education Secretary, has told the London Oratory, an 11-18 Catholic boys’ school in Hammersmith, that she is likely to approve its application to open a junior choir section. But she has rejected its plan to apply its existing admission procedures to the new pupils and has called in the head and chairman of governors for discussions.

The decision is conveyed in a letter from a senior Department for Education official, which makes clear that interviews are an unacceptable basis for selecting pupils and in breach of government guidelines. However, it ignores the fact that 11-year-olds are currently admitted on the basis of interviews.

The Oratory wants to be able to interview seven and nine-year-olds who can demonstrate average general ability and are suited to a specialist musical education. The intention is to run a specialist music course for 20 pupils a year, 10 of whom will be choristers.

The letter from the DFE points out that interviews should not be part of the selection because they involve an assessment that is “almost entirely subjective and is not acceptable”. As well as asking for radical changes in admissions policy, Mrs Shephard is suggesting the opening of the junior class should be delayed 12 months until September 1996.

It appears the DFE wants more details about the tests the school would use to determine general ability and whether the school will be requiring applicants to achieve a certain level of musical ability.

Where there is competition for places - all pupils will have to come from practising Catholic backgrounds - officials suggest selection should be on the basis of the rank order of the audition or musical test, provided, says the letter, the tests provide an objective means of doing so.

Mrs Shephard’s decision could lead to a further dispute over the school’s policy of admitting 11-year-olds on the basis of interviews, approved by the former Education Secretary John MacGregor in 1989. In December, it emerged that Blue Coat boys’ school in Liverpool - attended by the son of Labour’s schools’ spokesman Peter Kilfoyle - had been ordered to stop using interviews to choose pupils or apply to become selective.

The Oratory’s governors have already told the DFE they have no wish to drop the plan to interview pupils. According to John McIntosh, the head, the school believes strongly in interviews as a way of selecting pupils.

“We may not comply with the guidelines, but we are not in breach of any primary or secondary legislation. We have always interviewed and our admissions procedure (for 11-year-olds) was approved by the then education secretary, ” he says.

Mr McIntosh is critical of the fact that it has taken 11 months for civil servants to point out there is a problem with the admissions procedure.

The Catholic education service in Westminster, which had in the past queried whether the Oratory is complying with the guidelines, believes the latest decision to reject interviews for younger pupils, while doing nothing about the admissions procedure for 11-year-olds, lacks any logic. The Oratory is in the diocese, but is run by the Catholic Oratory Order.

Pupils are currently selected on the basis of an interview designed to assess whether the aims, attitudes, values and expectations of the parents and boys are in harmony with the school. Unlike most popular Catholic schools, the Oratory does not choose between pupils with equal claims on the basis of distance from the school. Hence it takes pupils from as far as Hertfordshire and Kent. The Blairs live eight miles from the school.

Martin Rogers of Local Schools Information, an advice service funded by the local authorities, describes the DFE decision as bizarre. “It rejects interviews for one part of the school, while ignoring a flagrant breach of their guidelines in the main school,” he says.

The DFE press office pointed out that the Oratory’s admission procedures were put in place in 1989, four years before the circular setting out guidance on good practice.

But the spokeswoman added: “The school is however aware of the Secretary of State’s view that Circular 693 advice on good practice should be taken into account in keeping admissions arrangements under review.”