The reliability of comprehension tests taken by 600,000 11-year-olds was called into question after a QCA official was found to have sparked the most serious attempt yet to cheat the system.
The official leaked information to a senior education officer in Wandsworth. The officer passed it to two colleagues, who began briefing the borough's primary schools in the run up to the test.
The Wandsworth investigation revealed that the QCA official knew the council officer as they had worked together at the QCA's predecessor, the School Curriculum and Assessment Authority.
The three council officials were suspended as soon as the leak was uncovered. The senior officer was demoted last week after a council investigation and disciplinary hearing. Her two colleagues were reinstated on June 17. All three were given severe reprimands and final written warnings.
The QCA has received a report of Wandsworth's investigation. A spokesman said: "Our inquiry into this matter is still continuing. No one has been suspended."
Up to half of the 60 primary schools in Wandsworth had advance details of the English test. Teachers who attended an in-service training course organised by the borough were given details. Headteachers were then telephoned by a Wandsworth officer who gave them information.
The attempt to cheat the testing system came to light after several headteachers complained.
Teachers had been told to revise the theme of "spiders" and that a comprehension exercise was based on a poem. The reading test included a factual piece on spiders' webs, a poem about spiders and a prose discussion of the Little Miss Muffet nursery rhyme.
The QCA learned of the leak at the end of April but decided to continue with the tests. It would have cost about pound;1.5 million to produce new papers at such short notice.