Exodus of seasoned educationists is threatening standards, say leading academics.
Fierce competition among rival bidders is forcing established teams of registered school inspectors to quit and threatening standards, academics have claimed.
The team from University of Wales Institute, Cardiff, has told inspection body Estyn that it cannot carry on in the current economic climate. Set up in 1993, UWIC's Celtic Inspection Services Unit conducted more than 60 inspections a year in its heyday.
Paul Thomas, dean of UWIC's school of education, told TES Cymru that registered inspectors are increasingly retired educationists ready to hang up their boots working from their front rooms.
"The fees of registered inspectors have diminished considerably over recent years," he said. "Things had reached a level where we would have to subsidise them if we were to continue."
About one-third of teaching staff in UWIC's school of education are trained inspectors.
Working for Estyn offered more than just a commercial opportunity, said Mr Thomas. "Our teams were senior lecturers and above, and it was valuable for staff development," he said.
Estyn-contracted teams include many from local education authorities, universities and other institutions. But with allcomers free to bid, Mr Thomas says that standards are at risk.
"It's very difficult to have quality assurance for inspectors," he said. "In the early days, training programmes were arduous and there was a sense of real quality.
"I understand teams have been coming in from England, yet Wales has a very distinctive education system that is hard to get your head around. The challenge of keeping up to date with educational initiatives and change is huge. What currency does the current system have in helping schools move forward?
"Historically, Her Majesty's Inspectorate was held in high esteem and known for consistency. I think schools take inspections less seriously than they did - there isn't the impact of HMI, which had subject experts who were respected and held in high esteem."
A review of the traditional inspection is on-going, with teaching unions backing the introduction of "softer" inspections based on evidence presented by the individual school.
But an Estyn spokeswoman denied that standards were slipping or inspections being done on the cheap. "In accordance with best practice, we've established standard competitive tendering procedures for contracts," she said.
"These are awarded on the balance of quality and price, and prices fluctuate as part of competition. Organisations and individuals can, and do, join and leave Estyn's contractor list at any time. As Estyn is bound by the Employment Equality Regulations 2006, it would seem discriminatory to imply a link between age and competence."
Estyn, she said, remains in close touch with schools through visits, research and meetings. It has also consulted widely on the future of inspection.
"We put a great deal of effort into training and updating - there are very few cases over the years of inspectors not meeting our standards," said the spokeswoman. "We also monitor quality - continued poor performance can result in de-registration.
"Initial training is less frequent than in the early 1990s, when the independent inspection system was first set up, but update training is as frequent as it was 10 years ago for team inspectors, and more intensive for registered inspectors."