On the floor above Sir Michael Barber's office is a white Portland stone balcony that offers one of the most impressive views in London.
Sitting just underneath the capital's biggest clock face, with the Thames below, it allows you to take in Britain's great centres of power with a quick turn of the head - from the financial muscle of Canary Wharf and the City in the east, to the Houses of Parliament in the west.
During the Second World War this was where Winston Churchill used to stand and watch Luftwaffe aircraft following the river to drop their bombs on London. At that time, it was briefly commandeered as the Ministry of Supply; today, the magnificent 1930s Art Deco slab that is Shell Mex House is at the centre of another empire - an empire of education.
And Barber, the former history teacher standing in Churchill's place, is at the heart of what some view as a new global battle for Anglo-Saxon values and the future of the world's schools.
This week, yet another batch of results from assessments of pupils' numeracy and literacy was released.
There is nothing unusual about that in today's hyper-accountable education system of targets, tests and tables. But Tuesday's results are published only every four or five years. They are not national but global, and come from schools in more than 60 countries, spread across six continents.
These are measures of effectiveness that could influence the development of entire nations. They can convey the kind of worldwide education superstar status that is currently enjoyed by Finland. Alternatively, they can ruin politicians' careers, trash pet projects and prompt prolonged bouts of national soul-searching.
The Trends in International Mathematics and Science Study (Timss) and Progress in International Reading Literacy Study (Pirls) may not be as famous as the Programme for International Student Assessment - better known as Pisa - but they are part of the same movement that, in the space of a decade, has transformed the way countries across the world draw up their education policies.
Andreas Schleicher, the Organisation for Economic Cooperation and Development (OECD) official who runs Pisa, remembers how education was seen by the world's power brokers in the mid 1990s, before such international comparative studies existed. "You had a meeting of about 30 education ministers sitting around the table and everyone would tell you `We have got the best education system in the world,'" he recalls. "If you have a meeting of ministers today, it will always start with `We have seen in Finland this and this', and `How did you actually do that?' It has really changed the debate. It has globalised the field of education. I think it has been very important."
Many people, not least our own education secretary Michael Gove, see this revolution as an undeniably good thing. They view the studies as providing valuable information about what actually works in education - evidence that policymakers would be negligent to ignore.
But others have serious reservations. These critics have concocted an acronym for what they see as an "illness" that is damaging schools around the world. They call it the Global Education Reform Movement - Germ.
Resistance is mounting to this "disease" among concerned educationalists from as far afield as Finland, New Zealand and Scotland. They are alarmed that its symptoms of competition, choice and constant measurements of teacher and pupil performance are leading to a homogenised, Americanised or anglicised global schools system that ignores many of the most important things in education. They argue that it has narrowed curricula, brought in an excess of testing and is making pupils' lives a pressurised hell.
"It is like an epidemic that spreads and infects education systems through a virus," according to Pasi Sahlberg, the Finnish education official who coined the acronym Germ. "It travels with pundits, media and politicians. Education systems borrow policies from others and get infected. As a consequence, schools get ill, teachers don't feel well and kids learn less."
Barber, unsurprisingly, disagrees. His story - how a former trade union official rose from fighting street politics for the Labour Party to advising Tony Blair in Downing Street and then became a knight of the realm, consulted by world leaders and sought after by a Conservative education secretary - is the story of how schools policy went global.
Born in 1955, Barber read history at Oxford and went on to teach the subject at secondary schools in Watford and Zimbabwe. After returning to England, he worked in the education department of the NUT, the most militant of teaching unions in the 1980s era of classroom strife and strikes.
During this period he joined the infamously "loony Left" Hackney Labour Party in East London and even unsuccessfully fought the 1987 general election.
But it wasn't until the mid 1990s that he really came into a position of power. By then he had risen to become the NUT's head of education and left for Keele University. In his role as an academic he was drafted in to help write New Labour's first education policy.
The programme he drew up with David Blunkett, the former shadow education secretary, was to become one of the most analysed and pored-over packages of reform in the history of world education.
It provided the meat behind Blair's famous 1997 "education, education, education" election pledge and interestingly, considering Barber's later conclusions, included an infant class size limit.
At its centre were the numeracy and literacy strategies - top-down, target-driven and massively prescriptive, and widely judged a success.
For Sahlberg at least, these strategies - together with the 1980s Conservative testing and table reforms they were built on - represented the birth of Germ. But the surveys that were to spread the movement had barely begun.
"When I was originally in the Department (for Education and Employment), when some international benchmarking came out, basically what we did was worry about where it would appear in the media," Barber remembers. "If we were good, we wanted to be on the front page and we ended up on page 17. If we were bad, we wanted to be on page 17 and ended up on the front page. And then we forgot about it until next time."
Assessment sparks change
He says the "big change" came with the first Pisa evaluation, conducted in 2000 and published in 2001.
It made comparatively good reading for those in UK education. But in Germany - which found itself much lower down the table than it expected - the impact was seismic and even led to the invention of a new noun, "Pisa- shock".
"The results were devastating," says Schleicher, remembering the effect on his own country. "But without the public concern that Pisa generated, probably very little would have happened.
"The financial investment of the government, the willingness of teaching unions to take a much more reasoned stance to reform, the interests of parents - all this has been instrumental in the remarkable improvements that have been achieved in Germany."
Schleicher says the response to the Pisa results improved the average progress of German pupils by the equivalent of half a school year.
Since then, Pisa has only got bigger and more influential. Barber has seen official reaction to such surveys moving from worrying about media coverage, through responding to disappointing performance, to a new phase - "a continuous dialogue among education ministers around the world".
And it is in this third phase that his own international influence has really taken off. In 2005, after a spell advising Blair on "delivery" in Number 10, he joined the global consultancy McKinsey (unofficial motto: "Everything can be measured and what gets measured gets managed").
The report he published for the firm in 2007, How the World's Best- Performing School Systems Come Out on Top, used Pisa's measurements to identify the "top 10" education systems and then analysed what had put them there.
With hindsight, its headline finding that "the quality of an education system cannot exceed the quality of its teachers" seems obvious. But at the time it was a wake-up call for countries that had invested billions in expensive policies such as reducing class sizes and achieved at best partial success. Why? Because they overlooked the importance of having good-quality teachers. The coalition government has made that principle central to its education policy and it is not alone.
Last year, Barber left McKinsey to become chief education adviser at Pearson, which uses Churchill's old wartime stomping ground as its head office and brands itself as "the world's leading education company".
With its services - from school improvement and textbook publishing, to exams, testing and curriculum development - provided in more than 70 countries, it is no empty boast.
But it is this integration of the private corporate world with public education that is part of what Germ's critics find so concerning.
"This process where education policies and ideas are lent and borrowed from the business world is often motivated by national hegemony and economic profit, rather than by moral goals of human development," Sahlberg has written.
Earlier this year, Barber revealed that during his time in Downing Street, between 2001 and 2005, he had tried to persuade Blair to allow state schools to be run at a profit. But his current role involves much more high-flown ideas about schools than mere profit.
In the third of his trilogy of reports on global education, published recently by Pearson, he argues that to allow "humanity to succeed in the next half century" the world's education systems must do more than simply impart knowledge. They must help pupils to gain "21st-century skills", such as leadership and collaboration.
To date, Barber has advised more than 40 of the world's governments on education and delivery. As far as he is concerned, the globalisation of education policy is "definitely a good thing".
"This is when you get into the evidence," he argues. "If you have got strong evidence that something works and then you choose not to do it, what is the ethical basis for that?
"It would be really surprising and actually quite bizarre in an education field to argue that not researching something and not learning about it is a better way to go than learning about it."
Schleicher also struggles to see any downside to Pisa and its ilk. "It has shown what is possible in education," he tells TES. "It has taken excuses away from those who are complacent."
So is this supposedly neo-liberal conspiracy to turn schools into money- making ventures for global business actually about nothing more than finding out what works?
It is Barber who pinpoints one of the more obvious problems with international comparisons. "None of it prevents a government reaching a crass conclusion on the basis of wanting to be like Finland or Singapore," he acknowledges.
Sahlberg believes that is exactly what is happening. But he does not see it as just an irritating side-effect; to him it is a major concern.
"A good, concrete example is in the Gulf states - the (United Arab) Emirates, for example - where they are purchasing national curriculum documents and entire systems from other parts of the world," he says. "Abu Dhabi is using the New South Wales curriculum because they want to be sure it is world class."
But why would that necessarily be a bad thing? Because, Sahlberg says, "these are completely different environments with different traditions".
New South Wales has "done a very good job" with its curriculum, he says, but only because it was "designed for their schools and their teachers and their thinking". Abu Dhabi, he insists, cannot rely on having the same kind of teachers as those working in Sydney schools in order to make the system work in the Gulf.
Sahlberg argues that his native country - Pisa star Finland - is often part of the same syndrome. Education tourists who want to import the Finnish system wholesale have to be warned that it will not necessarily work in a different culture without some of the best, most highly trained teachers in the world.
And he thinks there is an increasing risk of this kind of misunderstanding as Pisa expands to include more countries outside the OECD.
There are some systems that "aren't ready for this kind of OECD comparison" and "have a long way to go before the conditions are right", he argues, citing Tunisia, Azerbaijan and Qatar as examples.
"These countries have a completely different type of tradition than, for example, Scandinavian countries. It is difficult to believe that they would ever be able to get anything feasible out of this (Pisa) information," Sahlberg says.
The crude, simplistic appropriation of other countries' ideas went on long before international education surveys emerged, Barber counters, describing it as an "inevitable risk". But there seems little doubt that surveys such as Pisa have increased both the risk and the temptation for misguided quick fixes by clearly pinpointing the "top performers" that other countries may feel obliged to emulate.
Dismal and dangerous
For Stephen Heppell, who views Barber's reports as "dismal", the use of the data to rank countries in this way is "dangerous".
"You take the top five Pisa nations and say `Here are the top five world problems' and ask whether those nations have anything to offer in solving those problems, and there is a desperate mismatch," the Bournemouth University-based education technology guru has said.
Heppell argues that the Pisa figures are a "deeply flawed" way of comparing systems, and points to seemingly contradictory results from the 2007 Timss report, which suggested that UK pupils were top in Europe at that time.
Schleicher asserts that the two surveys are complementary and measure different things. But the fact remains that they are used to compile worldwide school league tables and are therefore likely to create the perverse incentives associated with any high-stakes performance measure.
And Schleicher admits that one of the most obvious drawbacks has already manifested itself. "Some countries have tried to game the system," he tells TES. "We had people in Germany, Switzerland, Spain, where (governments) thought `OK, we now know what Pisa is, so we should give our students more Pisa-type tests.'
"In the case of Germany, it was some state (governments) that produced booklets to familiarise students with Pisa."
Schleicher says this is firmly in the past: "We haven't seen anything like that in the past five or six years." But he seems unaware of a story that broke in Wales earlier this year.
The Principality is currently going through its own Pisa-shock, having been ranked below the rest of the UK at 30th out of 67 for science, 38th for reading and 40th for maths in the 2009 assessments.
In March this year, it emerged that the Welsh government had published a teachers' guide on how to incorporate Pisa into lessons. The news prompted immediate accusations that it was trying to prep pupils and "game" the tests, with unions concerned that it would lead to a narrowed curriculum geared solely towards Pisa.
But having been told about the teachers' guide by TES, Schleicher cautions that if the aim is to win Wales a competitive advantage then it is unlikely to succeed.
"It is a good thing to familiarise students with the nature of the task and we encourage that," he says. "But the idea that you can train performance or you can shortcut good instruction - I don't think there is any way to do that.
"Focus your efforts on good, high-quality instruction, that is what the best-performing systems show you."
But a quick route to a higher place in the tables is exactly what Wales is looking for. Education minister Leighton Andrews has set a target of reaching the top 20 by 2015 and has come up with a 20-point action plan to achieve it.
Schleicher's insistence that "I don't think the ranking has that much importance" seems to fly in the face of how Pisa is really viewed.
Justification for reforms
Gove has used England's apparent slip down the Pisa table between 2000 and 2009 as the main justification for his reforms, ignoring the fact that the 2000 data are, in Schleicher's words, "a little bit dodgy".
It is this fascination with headline rankings that particularly worries Sahlberg.
"Policymakers almost always only look at the rank their own country has in maths, science and reading," he observes. "The US is obsessed by this, you always hear that they are 12th in maths, 15th in reading and 27th in science.
"Pisa has so much more information - for example, on equity and equality - but people are not using this."
He, like the teaching unions that are sceptical about the Welsh Pisa action plan, believes the obsession is "leading to a narrowing of the concept of education". Sahlberg again points to the US, saying "there are states now where they don't require physical education any more".
It is a criticism that Schleicher initially appears to accept: "You can say of course that Pisa doesn't measure geography, doesn't mention art. There are important gaps in the knowledge base and I think that is something that Pisa will progressively resolve."
But he goes on to completely reject any suggestion that the focus on literacy and numeracy - "critical for the success of young people" - detracts from other subjects. "I don't accept that," he says. "I don't see that kind of conflict."
Another essential, but less understood, point about Pisa - which helps to explain why quick fixes are unlikely to work - is that it is not designed as a measure of school effectiveness.
"There are many different forms of a student's work - school is one, (but) it can be private tutoring, it can be learning reading outside school with parents - and we should look at this holistically," says Schleicher. "What you want is a child that is highly competent."
So if Pisa is measuring what is going on in homes as well as school then can it be a fair judge of the school system?
"I agree with the criticism that you can't say that the school system is entirely responsible for Pisa results," he admits.
But that, patently, is not how Gove, or Andrews in Wales, or many other schools ministers around the world view such surveys.
And it is that kind of misunderstanding or generalisation that goes to the heart of the problems that Sahlberg has with the international comparisons.
It is not the data that are produced by the likes of Pisa that are the problem, but the way in which they are used. And in that respect his frustrations are shared by Schleicher, who rails against the idea that you can "copy and paste" another education system, and Barber, who admits that "you can overdo the weight you put on Pisa".
In truth, the trio, who continually bump into each other at international conferences, have more in common than you might expect. Sahlberg may campaign against Germ but he is not against Pisa, Timss or Pirls. And he may be against an overly market- and competition-orientated approach to education but he is not against the global sharing of good ideas and practice.
He would like to see the kind of "trust-based" system that operates in Finland gain wider currency as an alternative to the Anglo-Saxon model.
In reality, the debate is not about the globalisation of education policy at all. It is too late for that, as shown by the air miles run up by the likes of Heppell, Schleicher, Sahlberg and Barber as they promote their takes on school reform.
For education, globalisation is already here. Now, the battle is about ideology.
Photo credit: Getty