The introduction of a banding system to measure the success or failure of schools in Wales was always going to be a fraught process. After all, the principality has been free of league tables for a decade.
But the repercussions are possibly more dramatic than even doom-mongers predicted. Indeed, heads' union ASCL Cymru, which is holding its annual conference this week, has claimed that a number of local authorities have threatened heads with the sack because of their schools' provisional banding places.
This could prove embarrassing for ministers, flying, as it does, in the face of the official line on the matter: that banding is designed to identify schools that need extra support from their local authorities.
The initiative places schools in one of five bands, based on GCSE results, attendance, progress and free school meals. Provisional banding positions were announced in September.
The fallout is already being felt. "Some of our members are already facing implied threats to their careers," said ASCL Cymru secretary Gareth Jones. "This is the 'sack the manager' culture we warned about when the system was first mooted. We have no problem with strong challenge, but it must be matched by equal support."
TES understands that one head, whose school was in band 4, was told to stop attending external meetings and concentrate more on running the school or face the sack. Another head in a different authority has been put under "considerable pressure" to quit following a poor inspection report and a low banding position.
It appears that some of the teaching unions' fears about the reaction of local authorities to the banding system are coming true.
"This has worried us from the beginning," said Anna Brychan, director of heads' union NAHT Cymru. "The whole point of a banding system was that we would be better able to support and challenge schools in a more targeted and expert way than in the past.
"A lot of feedback we have had suggests that, while the monitoring and targeting element has been taken up with some enthusiasm, there has been less enthusiasm about the support element."
Phil Dixon, director of teaching union ATL Cymru, urged the Welsh Government to "carefully police" local authorities so that its aims for the banding system are not "misrepresented". But, not surprisingly given the sensitivity over banding, central and local government have gone on the defensive.
"We have no evidence that local authorities have put heads under any unfair pressure and we are not interested in unsubstantiated accusations based on rumour," a Welsh Government spokesman said. "(We) will be monitoring the implementation of banding carefully through the School Standards Unit.
"We expect local authorities and consortia to be more pro-active in addressing issues of poor performance and we will ensure that the necessary support is put in place."
Chris Llewelyn, director of lifelong learning for the Welsh Local Government Association, insisted that local authorities do support the banding process.
"Banding is a mechanism to assess where a school is and what support they need," he said. "All along we have viewed it as a positive thing to raise standards and improve outcomes."
There is also evidence that some heads, presumably those whose schools are in the lower bands, are desperately trying to improve their banding positions by "playing" the system.
A leading head, who asked not to be named, told TES some of his colleagues are trying to encourage as many of their pupils as possible to take up free school meals to protect their scores. The banding model uses four groups of data, all of which take into account performance set against free school meal levels, so the higher the level, the better score a school will get.
Mr Jones said he was not surprised to hear that heads are trying to play the system, but his colleague Phil Whitcombe, head of Bryn Hafren comprehensive in Barry, Vale of Glamorgan, said their efforts were pointless.
"In a reasonable-sized secondary school you would have to find dozens of extra children just to increase your score by a small percentage," he said. "I would be very disappointed if heads were running around trying to sign extra kids up to free school meals instead of concentrating on teaching and learning."
HOW BANDING WORKS
Secondary schools are being placed into five bands based on their performance, from band 1 (performing well) to band 5 (in need of improvement).
The banding positions are based on data including exam results, attendance, progress made and levels of deprivation.
Local authorities will be expected to target extra support to schools in the lower bands, but there are no rules on this and no extra cash or resources will be provided.
High-performing schools will be expected to share their good practice to help low-performing schools.
Provisional banding positions were released in September and final information will be published next week. There are no plans to band special schools, but a primary model is being developed.