Ministers enjoy enumerating the schools that have taken up their offer to become academies. Since the coalition came to power there has been a near tenfold increase in the number of academies across the country.
But the government's figures hide a widespread reluctance among primary schools to cut themselves loose from local authorities. Barely half the expected number of primaries applied to become academies during the first two years of the coalition's time in office, despite a major drive to expand the programme.
The Department for Education had predicted that about 600 primaries would convert to academy status during 2011 and 2012, but just 325 took up the offer extended by education secretary Michael Gove in 2010.
The figures were revealed by the government's spending watchdog, the National Audit Office (NAO), which also said that the DfE is "not sufficiently prepared" to meet demand among secondary schools wishing to become part of the academy movement.
While more than half of all secondary schools are now academies, fewer than 5 per cent of primaries have converted. And the poor take-up is, according to primary heads, representative of a wider suspicion about whether the model works for the sector.
Russell Hobby, general secretary of the NAHT heads' union, said the figures show that academy status is not necessarily right for primaries, which is troubling when ministers are turning to the academy model to improve the worst-performing primaries.
"Secondary schools, with their huge management teams, their #163;5 million-plus budgets and dozens of teachers can't really be compared with a single-form-entry primary school that shares a bursar with three other schools," Mr Hobby said. "There is no evidence yet to say that primary academies will work.
"It is a concern (that the government is converting underperforming primary schools into academies) because you can't draw on a secondary school base of evidence and say it will work for all schools. It may well work for some, but as a robust and reliable tool for all schools the jury is very much still out."
Earlier this month, Prime Minister David Cameron announced that a further 400 of the weakest primary schools would be converted into sponsored academies in an attempt to boost results. They will join the more than 300 worst-performing primaries (judged by their Sats results) that were converted this year.
Penny Brown, head of Ash Croft Primary School in Derby, is supporting a weaker primary called Sinfin via a hard federation, in which the schools share a governing body. She said she would not like to stand alone as an academy.
"While we as schools support each other in Derby, I like that link we have with the local authority," Ms Brown said. "I like that there is someone I can go to and that someone I can trust is looking over me before Ofsted comes along."
The NAO said demand among secondary schools for academy status had caught the DfE by surprise, leading to a department overspend of #163;1 billion. Most was clawed back from local authorities and other parts of the DfE budget, but the miscalculation has left a #163;350 million hole.
NAO head Amyas Morse said that while delivering a tenfold increase in academies is a "significant achievement", the DfE is "not sufficiently prepared" for the costs of the programme or the challenges involved in overseeing so many new academies.
"It is too early to conclude on academies' overall performance, and this is something I intend to return to in the future," Mr Morse added. "As the programme continues to expand, the Department must build on its efforts to reduce costs and tackle accountability concerns if it is to reduce the risks to value for money."
See pages 52-53
Key figures from the National Audit Office report:
600 - Number of primary academy applications expected during 2011 and 2012.
325 - Number of applications actually received from primaries.
#163;1bn - Department for Education overspend because of academies programme.
#163;350m - Shortfall in Department for Education budget.
2,456 - Number of academies now open in England.
#163;6,600 - Difference between salaries of academy heads and their lower-paid state school peers.
6 - Number of academy chain leaders paid at least #163;200,000 last year.