The funding gap between pupils in England and Wales has become a key battleground for Welsh politicians since it was first exposed by TES back in 2008.
In last year's Assembly elections campaign, education minister Leighton Andrews pledged to cut the disparity, which meant that pupils in Wales received #163;600 less than their peers in England in 2011.
So it was with considerable embarrassment that Mr Andrews had to admit last week that the latest figures could not be published. Statisticians have told him that comparisons can no longer be made - and have blamed the pace of change at Westminster for the problem.
Mr Andrews claims to be "profoundly disappointed" that the figures cannot be published, even though they were widely expected to show that the gap had continued to grow. Opposition politicians have accused the government of a "cover-up".
A spokeswoman for Kate Chamberlain, the chief statistician, said that she was "aware of the interest" in the comparison but that it had not been possible to compare the 2011-12 budgets. She blamed the "changing education policy landscape in England" as well as the large numbers of schools moving to academy status.
Angela Burns, shadow education minister, said that failing to publish the figures "flies in the face of transparency".
"Even without the latest figures, we know that the funding gap between Welsh and English schools has been widening and most recently stood at more than #163;600 per pupil," she said.
"With well-documented failings in school standards in Wales, parents should be entitled to see the extent to which Labour is underfunding our schools."
When Labour won last year's election, teaching unions sent them a unanimous message to make funding schools its number-one priority. Given the rhetoric, it is no surprise that last week's sudden announcement was met with anger.
Rex Phillips of the NASUWT accused Mr Andrews of "burying" the figures and said he should "bow his head in shame", and NUT Cymru secretary David Evans said he was "extremely disappointed" and suggested that the decision meant that the gap had widened further.
Dr Philip Dixon, director of ATL Cymru, said: "I am astonished both by the content of the announcement and also by the cavalier way in which it has been made."
A government spokesman was forced to make a statement on behalf of an embattled Mr Andrews.
"Whilst accepting this is a matter for the chief statistician to decide, the minister is profoundly disappointed with the decision and has made clear that he does not agree with it," he said.
"He is now actively exploring other options to obtain the necessary data to make the comparisons between the two education systems public in a similar format to previous years."
Mr Andrews' efforts to turn the situation to his advantage and attack the Tory-led Westminster government also seem to have backfired.
His spokesman said that if it was true that spending figures were no longer available in England, then it was a "quite incredible" admission from the UK government that it had no way of tracking spending on academies. This would be a "serious concern" for pupils, parents and teachers in England, he said.
But a Department for Education spokesman said academies are required by law to produce and publish audited annual accounts, which are available to the general public. "A straight comparison is possible but will require detailed and careful analysis," he said.
Mind the gap
In 1999-2000 England spent just #163;58 more per pupil than Wales, a 2 per cent difference. The gap in spend per pupil has increased year on year:
#163;496 2008-2009 (9.6%)
#163;527 2009-2010 (10.1%)
#163;604 2010-11 (10.8%).