Tony Blair has tried to neutralise the Harriet Harman debacle by reiterating the party’s commitment to the comprehensive principle. “There will be no change to the Labour party policy on selection. . . no going back from our commitment to comprehensive education,” he told the shadow Cabinet last week. This sounds suitably uncompromising, but raises the question of what exactly is meant by selection in a system which contains many anomalies in admission arrangements.

The city technology colleges introduced by former Education Secretary Kenneth Baker in 1988 encapsulate many of the contradictions in the debate on selection. On the face of it, the 15 CTCs are independent (though not fee-paying) selective schools, choosing their pupils through a combination of interviews and tests - both of which David Blunkett explicitly outlawed at the last Labour conference. However, in sharp contrast to St Olave’s, the school Harriet Harman chose, the purpose of those interviews and tests is to ensure that the CTC has a genuinely comprehensive intake.

All prospective entrants are selected from an area within reasonable travelling distance and given a basic non-verbal IQ test to ensure that the range of ability in the school is representative of the general population. This is followed by an aptitude test, usually involving a practical task or test of spatial awareness, to find out whether the child would be suitable for the CTC-style education. Principals of CTCs admit that this is difficult as there is no watertight test for technical aptitude or reliable way of ensuring that advantages conferred by background are screened out, but the heads insist vehemently that they are as fair as possible. Parents are then interviewed to establish that they understand the differences between CTCs and other schools (such as a longer school day and a five-term year).

“Far from creaming off the best pupils, we select in order to create the perfect comprehensive,” said John Burn, principal of Emmanuel College in Gateshead, while Cyril Taylor, chair of the CTC Trust, argues that selection as practised by CTCs is more democratic in its effects than the catchment system which discriminates in favour of wealthy, mobile parents able to move near to the school of their choice. “It’s middle-class selection by default, while our arrangement resolves the whole issue of selection rather neatly.” Labour, he hinted darkly, is “pretty interested in CTC-style selection”.

With a future Labour government looking possible, the CTCs are naturally keen to point out how well their aims and ethos would fit into Labour’s plans. While the Labour party has repeatedly indicated that it has no objection to the rapidly expanding technology and language colleges programme now that specialist status is available to local authority as well as grant-maintained schools, its plans for CTCs are vague.

The only explicit reference to the future of CTCs in the policy document Diversity and Excellence comes right at the end where it suggests that, like grant-maintained schools, they would probably be attracted to the proposed “foundation” status under Labour. If so, they could have to accept some local authority input on the governing body and would lose control over 10 per cent of their budget.

Any attempt to force CTCs into foundation status and within the ambit of local authorities could be challenged in the courts - CTC trusts are covered by a legal clause which protects them from change for seven years. Graham Lane, education chair of the Association of Metropolitan Authorities, is currently engaged, with the approval of David Blunkett, in “very amicable” discussions with Cyril Taylor and the CTC Trust.

“We all want to solve this conundrum,” he said. “Relations between CTCs and their local authorities vary, but I don’t think CTCs want to be left out in the cold.” The question of what is to happen about selection, he suggested, is likely to be more of a sticking point.

Many of the CTC heads believe they have little to fear from a Labour government provided that Labour understands what CTCs are doing. None of the colleges contacted by The TES had received any definite information on Labour’s plans.

At Bacon’s CTC in Southwark, principal Tony Perry said that the initial hostility from local authorities had dissipated. “The world has moved on since we opened; we now have a very good relationship with Southwark and use its inspectors. Like GM schools, we expect our funding base to change, but we’re prepared for that.”

Keith Standley at the BRIT Performing Arts and Technology School in Croydon also thinks that “there is a broad cross-party consensus” that schools such as his are doing a good job, as did Keith McCorkindale at The John Cabot CTC in Bristol: “We’re happy to take part in the debate about parental choice and where specialist schools fit into that - we recognise that we have to adapt. ”

But John Burn at Emmanuel College in Gateshead was less sanguine: “There are very serious implications for us if we have to lose 10 per cent of our budget - in practice this would be a third of a million a year.” He was also worried that Labour might impose a dogmatic interpretation of a no-selection principle: “If we were forbidden to select by test and interview, we would not have this perfectly comprehensive school.”

The idea that interviews favour middle-class parents is “highly patronising”, he says. “We are faced with 400 applications for 150 places. Most of these are from working-class parents and they are all articulate and able to state what they want. It’s a good thing in itself if parents are interviewed.”

John Lewis, who chairs the forum of CTC principals, drew attention to the remarkable change of heart by Labour and LEAs over specialist schools, but offered a guarded warning to Labour: “We are doing all the things that Labour wishes to do in its crusade to raise standards, but we have never been part of the local authority and would not welcome losing 10 per cent of our budget. ” Labour, he said, had underestimated the complexity of the legal basis on which CTCs were set up: “they have assumed that there are no differences between CTCs and GM schools, but GM schools have opted out of the LEA - we were never in.”

Cyril Taylor said he thought it unlikely that Labour, with an entire education service to sort out, would “waste a lot of time on just 15 schools - provided we maintain good relations with the local areas.”