Four major inquiries have published their findings following claims that a group of conservative Muslims are taking over a number of schools in Birmingham.
The anonymous, so-called Trojan Horse letter included advice on installing sympathetic school governors.
The controversy continues to prompt local and national reaction. Follow a timeline of events as they unfolded.
7 March 2014
Birmingham City Council reveals it is investigating a number of schools in the city after receiving a copy of an anonymous letter referring to Operation Trojan Horse - a plot by some Muslim groups to install governors at schools. It claims responsibility for ousting four head teachers.
The Department for Education (DfE) confirms it is also investigating.
17 March 2014
Ofsted turns up at Park View Academy - one of the schools implicated - for a snap inspection.
Two years earlier the predecessor school on the site had been graded outstanding. "All schools should be like this," Ofsted chief Sir Michael Wilshaw had said in March 2012.
31 March 2014
The DfE says it is looking into claims the Operation Trojan Horse plot targeted 12 schools.
9 April 2014
The governors of Park View Educational Trust describe the ongoing investigations as a "witch-hunt" .
14 April 2014
Birmingham City Council says it is looking into allegations involving 25 schools in the city, including primaries, secondaries and academies. Council leader Sir Albert Bore says he does not believe there is a "plot".
15 April 2014
West Midlands Police condemn the DfE's decision to appoint a former national head of counter terrorism to carry out its investigation for the message it sends
20 April 2014
Sir Michael Wilshaw takes personal charge of Ofsted's Trojan Horse investigations.
3 May 2014
Sir Michael says Ofsted has inspected 21 schools in Birmingham.
3 June 2014
Three of the schools under investigation publish their Ofsted reports.
Ninestiles and Small Heath are rated as "outstanding" and Washwood Heath as "good".
4 June 2014
Home Secretary Theresa May accuses Education Secretary Michael Gove of failing to deal with an alleged Islamist plot to take over schools.
In a letter she asks whether it is true that the DfE was warned about the allegations in 2010 and Birmingham Council as far back as 2008.
9 June 2014
Ofsted places five schools in special measures and confirms that a sixth (which was already in special measures) is "inadequate".
Sir Michael says there is evidence of an "organised campaign to target certain schools" and finds that some governors attempted to "impose and promote a narrow faith-based ideology" in secular schools.
The schools involved deny any wrongdoing.
10 June 2014
Two academies - Park View and Nansen Primary - are told they will lose funding, while Oldknow Academy and Golden Hillock School are warned they too could lose funding unless concerns are addressed.
10 June 2014
Ofsted head Sir Michael says the experience in Birmingham could lead to snap inspections at schools across the country.
15 June 2014
At a public meeting, parents of pupils at Park View Academy call for governors at the school to stand down.
Vice-principal Lee Donaghy, however, said governors had been behind many of the changes that saw the school rated as outstanding by Ofsted in 2012.
16 June 2014
The Park View Educational Trust, which runs three of the schools put in special measures, accuses the government of "deliberately misrepresenting" schools and describes inspections as "woefully shoddy" and "fatally flawed".
4 July 2014
Governors at Golden Hillock School say they were not given enough time to make improvements before a visit by Ofsted.
15 July 2014
The board of trustees at Park View Education Trust resign. Its chairman Tahir Alam says the decision was made in the interests of the children.
He said a "co-ordinated and vicious" attack by former Education Secretary Michael Gove and the Department for Education had left the three-member board with no choice but to step down.
Waverley School head teacher Kamal Hanif, Greet Primary head teacher Pat Smart and King Edwards VI Five Ways head teacher Yvonne Wilkinson agree to serve on the new trust.
17 July 2014
A leaked copy of Peter Clarke's report for the DfE finds evidence there was an agenda to introduce "an intolerant and aggressive Islamist ethos" into some Birmingham schools.
Details of the report by the former counter-terrorism chief were leaked to The Guardian newspaper.
18 July 2014
Birmingham City Council releases key findings from its inquiry into 25 schools, prompting reaction from head teachers and others.
Written by Ian Kershaw, it finds no evidence of violent extremism, radicalisation or an anti-British agenda being promoted. However, it does warn of governance problems in some schools.
Mr Kershaw also criticises the council's role in supporting the schools involved.
21 July 2014
Birmingham MP, Khalid Mahmood, says teachers forced out of schools involved in the Trojan Horse allegations deserve to be compensated.
He claimed at least 12 senior school staff had been bullied or forced out of their posts.
22 July 2014
Peter Clarke's report for the DfE is officially released.
Mr Clarke says his inquiry found no evidence of extremism but "there are a number of people in a position of influence who either espouse, or sympathise with or fail to challenge extremist views".
24 September 2014
Sir Mike Tomlinson is appointed Education Commissioner for Birmingham by the government.
8 January 2015
Ofsted says there are still concerns at Park View Academy following a monitoring inspection.
30 January 2015
MPs criticise a lack of oversight for previously high-achieving schools.
10 February 2015
Head teachers highlight a lack of central record keeping and propose a database of school governors.
17 March 2015
The Education Select Committee criticises a lack of coordination between the various Trojan Horse inquiries and suggests there was no evidence of a plot.
24 March 2015
Ofsted says three out of the five schools placed in special measures are making "reasonable progress".
27 June 2015
The DfE criticises the Education Select Committee for "downplaying" the seriousness of events in Birmingham and "undermining" efforts to tackle extremism.
30 June 2015
The government announces that a national database of school governors in England will be set up.
14 July 2015
Ofsted chief Sir Michael Wilshaw warns of "potentially high numbers of pupils" disappearing from school registers in Birmingham and Tower Hamlets in east London, after follow-up visits prompted by the Trojan Horse inquiries.
In a letter to the secretary of state for education, he also said the picture in Birmingham was "improving slowly", although problems remained at schools placed in special measures.
15 July 2015
Birmingham's education commissioner Sir Mike Tomlinson says the anonymous Trojan Horse letter was "no hoax".
Speaking to BBC Midlands Today, he said he believed the letter was genuine.