Firms supplying inspectors to the Office for Standards in Eduction are rushing to tie up freelancers on permanent contracts for the new short-notice, lighter-touch regime that comes into force in September.
They are advertising full-time inspector posts with salaries of around Pounds 50,000.
School inspections will be carried out by just five companies as Ofsted tries to cut costs by relying on schools to do more self-evaluation.
The need for high-quality staff at short notice means that for the first time since Ofsted was created in 1992, most inspections will be carried out by full-time inspectors.
But many experienced inspectors in their 60s are expected to resist pressure to go full-time. They will have to compete for a limited amount of freelance work which could include private-school inspections and evaluations of government initiatives.
John Chowcatt, general secretary of the National Association of Educational Inspectors, Advisers and Consultants, said: "We are very anxious that alternative work is put in place, but it will not be enough to compensate for school inspection work."
Ofsted said the new four-year contracts with providers will deliver savings of about pound;15 million per year. The cut in the number of contractors from 24 to five is the latest rationalisation of the inspection market that has seen a dramatic drop in the number of firms providing inspectors.
Each of three regions - the North, the Midlands and the South - will be supplied by two firms (see box). Capita, one of the biggest names in education, has failed to win a contract.