Those successful included the Pre-School Learning Alliance, with 150 contracts; Cambridge Education Associates (50); Kinderquest of Wellingborough (60), and Anglia Polytechnic University (35).
The news that the PSLA had bid for such an ambitious number of contracts and had been so successful surprised some early-years specialists this week.
But Group 4, the company administering the bids, said many of the 12 operated from a single area, whereas organisations such as the PSLA had contacts nationwide.
Margaret Lochrie, the Pre-School Learning Alliance's chief executive officer, said: "I do not know what other people bid. We did not set out to under-bid. "
There are suggestions from some quarters that the PSLA lacks the in-depth educational experience to handle so many inspections. But the early-years workers from the group's 20,000 pre-schools in England have the advantage of grassroots experience.
Successful contractors contacted by The TES were tightlipped about the cost of their inspections but it is understood that a typical figure would be about Pounds 800.
* Capita, the company managing the nursery voucher pilot, has beaten 95 rivals to win the contract for the national version of the scheme. The company, which also holds the contract for the Teachers' Superannuation Scheme, intends to manage the national nursery voucher scheme for less than Pounds 10 per child. The contract is worth about Pounds 15 million over three years.