Wales's director of education Steve Marshall has resigned his post for a new life in Canada.
His shock departure to Ontario - a province renown for its educational excellence - will come as a major blow as schools in Wales prepare for their most challenging year of curriculum change this decade.
The 53-year-old Australian has accepted a "once in a lifetime" job offer as deputy education minister.
It means he is leaving Wales at a critical time in the delivery of his own visionary educational reforms.
In a statement written for TES Cymru just before Christmas, Mr Marshall said his decision to leave was one of the most difficult he had ever had to make.
The move comes just two years after he was appointed by the Assembly government to lead the former department for education and lifelong learning, a product of the so-called "bonfire of the quangos" that absorbed the Welsh qualifications, curriculum and assessment body ACCAC.
"I hope the new department of children, education and lifelong learning and skills (DCELLS) will be a stronger and more outwardly focused organisation," he said.
But speculation was rife this week that Mr Marshall's decision to leave Wales could have been prompted by growing frustrations over financial constraints. There are also claims that he may have encountered some hostility to his shake-up plans. Called tri-level reform, the former headteacher believed only co-operation between officials, local authorities and schools would turn around educational outcomes in Wales.
However, there was growing discontent from teaching unions, local authorities and schools over lack of funding for major curriculum reform in 2008, including the threat of strike action.
Mr Marshall was about to see through the next stage of tri-level reform, called the School Effectiveness Framework.
Professor David Reynolds of Plymouth University said he hoped the programme would not become a casualty of Mr Marshall's departure. "Mr Marshall is a straight-talking person in a culture that finds truths hard to handle," he added.
The Wales-based academic also believes the country's dire performance in the international Pisa tests for the maths, reading and science skills of 15-year-olds, which put the nation on a par recently with Croatia, could have validated Mr Marshall's decision to leave.
Canada, by contrast, is in the top five-performing countries for all three Pisa subjects.
Education minister Jane Hutt said Mr Marshall had made an "enormous contribution" to Welsh education. She insisted his tri-level reforms would continue.
More reaction, page 3.