Rarely has an issue been so unifying in education. Everyone, it seems, is demanding big changes at Ofsted.
Some want to see the inspectorate abolished altogether. Others would like it to be split in two. But the desire for major reform at the embattled watchdog runs right across the political spectrum, taking in school leaders and classroom teachers, their union representatives, politicians, bloggers, thinktanks and even Ofsted itself.
"If we are still around in 10 years' time, I think the way we inspect and the structures by which we inspect will be very different," Her Majesty's Chief Inspector Sir Michael Wilshaw told MPs earlier this year.
But the need for change is where that consensus ends: the two biggest political parties have gone into the general election campaign with very different ideas of how to reform the watchdog. There are also conflicting views on who should succeed Sir Michael as chief inspector. Many do not expect the 68-year-old to be in his post 10 months from now, let alone 10 years.
That speculation may be a little premature. The lauded former headteacher is currently recovering from surgery but is already understood to be making plans for returning to work. Nevertheless, would-be successors are being touted, and Sir Michael's own comments suggest he is unlikely to be in it for the long haul. He was managing expectations back in 2011, before he had even started at Ofsted, suggesting to TES that he might not serve the usual five-year term: "Given that I am of a certain age .it could be shorter."
In the event, the chief inspector, who quickly antagonised teachers' leaders with his plain-speaking comments after joining Ofsted in January 2012, signed a contract to keep him at the inspectorate until 2017.
Things had been "tough", Sir Michael said just 18 months later as he again suggested a possible early departure. And they have only got tougher since. Over the past two years, Ofsted has come in for an unprecedented level of criticism. Sir Michael has become the most controversial chief inspector since Chris Woodhead and, even more damagingly, he apparently lost the confidence of those in government who appointed him.
There was the semi-public row with ministers over their decision to oust Sir Michael's ally Baroness Morgan as chair of Ofsted, and his admission that he was "spitting blood" over suspicions that the Department for Education was briefing against him. Meanwhile, the inspectorate was being criticised by right-leaning thinktanks and left-leaning union leaders, and accused of having "dropped the ball" over the Trojan Horse controversy in Birmingham.
Ultimately, though, it is measured academic challenges - going to the heart of the inspectorate's core purpose - that have probably done the most damage.
Professor Dylan Wiliam, from the UCL Institute of Education, led the charge, telling TES in February 2012 that Ofsted needed to show more "humility" and should prove its "integrity" by subjecting its school inspections to a proper evaluation of their reliability. The academic claimed that the watchdog did "not know good teaching" when it saw it.
Durham University's Professor Robert Coe took up the baton the following year, stating that the watchdog was "part of the problem". Its practice was not research- or evidence-based, he said, and it needed to demonstrate that its lesson evaluations were valid by testing whether different inspection teams produced consistent judgements of schools.
That warning was picked up on by Dominic Cummings, special adviser to Michael Gove, then education secretary. Mr Cummings was already worried about Sir Michael's leadership. A month later he wrote an internal DfE memo, leaked last October, noting that senior department figures were "increasingly alarmed" and that it was "worth thinking about the whole Ofsted approach with a blank sheet of paper".
Sir Michael hit back, saying the leak confirmed his suspicions about "plots and smear campaigns". But it was more difficult to bat away a determined campaign from teacher-bloggers, who argued that Ofsted was showing bias towards particular teaching styles.
In the end, the watchdog went on a charm offensive. Online critics were invited for conciliatory talks at its London headquarters, and new guidance was issued backing up Sir Michael's insistence that there was "no right way to teach".
But the serious criticism of the fundamentals of Ofsted did not go away. Another former adviser to Mr Gove - Sam Freedman, now at Teach First - and two thinktanks called for Ofsted inspectors to stop making judgements about teaching quality.
Today Ofsted remains "in a bad place", according to Professor Chris Husbands, director of the UCL Institute of Education. But he doesn't believe that a drop in the quality of inspection is to blame. He thinks it is because the stakes have been raised by ministers.
"One of the big problems of the past 20-odd years has been the way in which governments have put more and more emphasis on Ofsted inspection both at the top and bottom end," he says. "If you are outstanding you get to be a teaching school - you get to lead change in other schools. If you are the bottom end you get taken over. So it is not surprising that Ofsted's methods are under far greater scrutiny."
The academic notes that the inspectorate's budget has fallen dramatically. He believes that Sir Michael has "done quite a good job" in the circumstances but that further reform is needed. And Professor Husbands thinks that may have to happen under a new chief inspector because he suspects the current one "would now dig in".
But it would be unfair to portray Ofsted as resisting all change. If it was initially slow to respond to criticism, the watchdog appears to have learned the lesson and is now going out of its way to show it can transform itself. Ofsted no longer grades individual lessons; its system of outside contractors is being scrapped, with all inspectors being brought in-house and more serving headteachers recruited; and it has begun to experiment with assessing the reliability of its inspections.
In September, Ofsted will follow this up by introducing yet another new inspection framework, including shorter but more frequent visits for "good" schools. However, most critics - and they include those who will be at the heart of the next government whatever the election result - still believe it is not enough.
Jonathan Simons, head of education at the right-leaning thinktank Policy Exchange, wants lesson observations to be dropped from inspections completely, arguing that their existence "just muddies the waters".
"What are they attempting to do?" he says. "Are they making a judgement on quality of teaching? If so then you get back to all the issues about `On what basis they are making that judgement?' If they are not making a judgement about quality of teaching then why are they doing it?"
Meanwhile, headteachers' unions have called for the end of the "outstanding" grade, with the NAHT arguing that excellence should be defined by the profession and not a regulator.
Professor Husbands similarly argues that Ofsted judgements on schools could be confined to a simple pass or fail. But he would like to see more senior inspectors given a parallel role of looking at "trends and performance across the system", in the way that Her Majesty's Inspectors used to, to help inform government policy.
Sir Mike Tomlinson, a former HMI who went on to become Ofsted's third chief inspector, recently told TES that school inspection today is too inconsistent and too data-reliant (" `Inspection is so important - have we got it right?' ", News, 3 April). These are faults that the watchdog's national director for schools, Sean Harford, has publicly admitted to.
But ministers will not necessarily be on the same page. If the Conservatives lead the next government, they intend to reform Ofsted so that it makes even more use of data, not less. They argue that this would allow it to be less reliant on inspections and therefore relieve the burden on teachers.
Shadow education secretary Tristram Hunt, on the other hand, is promising that Labour would deliver an Ofsted that goes "beyond box-ticking and data dependence". He believes that a move towards a system of Ofsted-moderated peer review - which Mr Harford and Sir Michael say is a decade away - is possible in just five years.
Giving schools a key role in monitoring each other's performance is not something the Tories are entirely opposed to. But they are concerned about the workload and resource implications of peer review for schools, and feel it is still some way off.
Mr Simons of Policy Exchange argues that if peer review ever did become part of the inspection system, strict quality assurance would be needed to prevent it becoming a "cosy club". But he is interested in the concept, particularly to distinguish good schools from excellent ones.
He also wants to end the exemption from inspection for outstanding schools and believes that Ofsted should be split in two, with separate chief inspectors for education and social care, because "the agendas are so big but they are also quite different".
The Green Party and the NUT teaching union would like to scrap Ofsted altogether. But is doubtful whether any government would be prepared to go that far. Apart from anything else, the Conservatives believe it is still a brand that parents trust, a point echoed by Professor Husbands.
"Although it is pretty unpopular with teachers, it is actually very popular with parents," he says. "Parents find Ofsted reports useful - they read Ofsted reports. So it is inconceivable that it would be abolished."
The Tories also appear more positive about Sir Michael now that Nicky Morgan has replaced Michael Gove as education secretary. "Sir Michael and Nicky have a great working relationship which has actually gone from strength to strength," a well-placed Conservative source tells TES.
Mr Hunt has been similarly upbeat about the chief inspector, describing him as "a progressive force for good" and "a headteacher's headteacher" who understood the need for Ofsted to "evolve and change".
But although Sir Michael seems almost certain to be in place immediately after the election, some question whether he has the stomach for the change that must inevitably follow. "He has taken Ofsted as far as he can take it," one observer says. "He has done his big thing - he changed the framework - so I don't think he would be up for another big push."
Professor Coe agrees. He is also unimpressed by how an "amateurish" Ofsted has responded to the debate he helped to start, describing some of its changes as "superficial and cosmetic". "I almost regret raising the [lesson observation] issue," he adds. "[Ofsted] are now doing something that is every bit as dodgy.
"They said, `We are not going to grade individual lessons but we are going to look at other things.' So the perception out there is that they look at marking and see what kind of work students are doing.
"That is every bit as unreliable and unsound as practice. It isn't any better than observing lessons."
The answer, Professor Coe argues, is to follow the example of the Netherlands and Germany. Inspectors there have more of a research background and link what they look for when observing lessons more closely to research evidence, he says.
"I understand that would be a long journey for [Ofsted] because there is a big cultural change there," he concedes. "But it is relatively easy. They just need to decide to do their job properly."
Read more about Ofsted here
The inspectorate responds
Matthew Coffey, chief operating officer at Ofsted, writes:
September 2015 will see the biggest change to the way Ofsted inspects since its creation in 1992.
Outstanding schools and colleges are already exempt from routine inspection. From September, good schools and colleges will have shorter HMI-led inspections that will focus on whether a good standard has been maintained. This will reduce the high-stakes nature of inspection for the vast majority of institutions.
We are also radically changing the make-up of the inspection workforce. From September, we will contract directly with inspectors rather than through third parties. We will have tighter control over selection, quality assurance and training. And a much higher proportion of inspectors will be serving leaders.
We want to work with the sector to establish greater ownership of a high-quality inspection system that maintains the rigour and independence that parents and learners expect and deserve.
Who could replace Sir Michael as chief inspector?
Jon Coles has already been publicly suggested as the most likely Labour candidate. The former DfE director general for education standards was reportedly his department's pick when the job came up last time round. Now chief executive of United Learning, he oversees 40 state-funded schools and 13 in the independent sector. He is also a qualified secondary school teacher.
Sir Daniel Moynihan, a fellow academy chain chief executive - heading the Harris Federation - would be an obvious Conservative favourite. But many doubt whether he would want to take a pay cut. In 2013-14, his earnings were reported to be pound;375,611.
Professor Chris Husbands, director of the UCL Institute of Education, is another suggested Labour candidate; he helped the party to pen the education section of its election manifesto. But he sounds almost embarrassed when TES asks if he wants the job. "No! I know my strengths and I know my weaknesses," he says. "No."
The academic adds: "I think the appointment of Michael [Wilshaw] means it would now be quite difficult to appoint somebody who had not been a recently successful headteacher."
A headteacher would also be the prediction of many others. "You have got to have the credibility of the schools," one observer notes, arguing that the obvious recruitment pool has shifted from local authorities to school leaders. "That's where most of the power lies and where most of the talent is migrating to," they add.
Sir David Carter seems an ideal choice for those who believe the next chief inspector should not have run a single school but managed a group of them. He was approached in 2011 but ruled himself out, citing unfinished business as chief executive of the Cabot Learning Federation. But Sir David has since left the Bristol academy chain. Now regional schools commissioner for the South West, he has thrived under Conservative and Labour administrations.
Dame Alison Peacock, executive headteacher of the Wroxham School in Hertfordshire, has been mentioned as a Labour possibility.
Ian Bauckham, former president of the Association of School and College Leaders, has been suggested by several sources as a favoured candidate among headteachers' leaders.
Dame Sally Coates, United Learning's director of secondary academies in the South, would be on any Conservative shortlist, according to a well-connected source, who says: "There is a lot of love out there for Sally."
Russell Hobby, general secretary of the NAHT headteachers' union, may never have served as a teacher, but he is well-respected across education and knows the sector intimately.
Dr Kevan Collins, chief executive of the Education Endowment Foundation, could have similarly broad appeal. And the affable former primary teacher has plenty of management experience, having served as chief executive of Tower Hamlets Council. Dr Collins brushes off suggestions that he would be offered - or take - the role, but he does have views on how it should change. "We need to shift the focus away from that individual," he says. "It needs to be a slightly more boring corporate enterprise. I want to de-politicise it. I want it to be more about the hard grind of school improvement. We should let the politicians be the politicians."
"Ofsted dropped the ball when it stopped inspecting how schools tackle race equality."
Chris Keates, NASUWT general secretary, responding to Birmingham's Trojan Horse schools controversy
"All top DfE officials know Ofsted is broken but No 10 is stopping the DfE from acting cos `keep quiet for election'."
Tweet from Dominic Cummings, special adviser to Michael Gove when he was education secretary
"Almost nobody in education now has a good word to say about Ofsted."
Professor Chris Husbands, director, UCL Institute of Education
"When it comes to relying on the judgement of a trained Ofsted inspector on how effective a lesson is, you would be better off flipping a coin."
Jonathan Simons, head of education, Policy Exchange
"Frankly, the game is up for Ofsted. It is a busted flush. Ofsted can no longer claim that its inspection reports are worth the paper they are written on."
Mary Bousted, ATL general secretary
"Ofsted do not know good teaching when they see it."
Professor Dylan Wiliam, UCL Institute of Education