That, in part, is because of sheer size, he said. England's elementary and secondary educational system, which has about 7 million students and 24,000 schools, he said, is more akin to California's, which has about 6.3 million students and 9,500 schools, than to the entire US system, which has about 50 million students and 90,000 schools.
But more important, he said, Britain's political system endows its prime ministers with greater powers to impose new practices than any corresponding US official enjoys, since basic education policies in the US are set in the 50 states and in the nation's 15,000 local school districts. Even though US President George W. Bush's No Child Left Behind law has considerably increased federal influence over what happens in US schools, Washington still plays a subsidiary role to states and municipalities, he said.
"Once Britain's prime minister is elected, he has a majority in parliament and it's much easier to change things," Barber said. "In contrast, the Founding Fathers created a political culture where you have to get consensus from competing factions."
In Ohio, for instance, Barber led a McKinsey team last year that helped produce a 102-page report recommending new education policies based on the best practices in Britain and other countries.
But for the state to put its recommendations in place in a coherent way, he said, would require an unlikely alignment of galaxies: The Ohio Board of Education, the state's new Democratic governor and its Republican-dominated legislature would all have to cooperate closely.
"And that's not to mention Ohio's 613 school districts," he said. "So it's a real challenge to align all these actors behind that reform."
In Blair's Britain, it was possible to impose a new policy quickly. From 1997 through 2001, when Barber headed the Standards and Effectiveness Unit of the Department for Education and Skills, he presided over the shuttering of some 130 chronically low-performing English schools.
No US state has addressed its failing schools with a vigor that is even remotely similar, even though under No Child Left Behind, about 1,800 of the nation's schools have been identified as in need of overhaul. So far, none of the 50 states have even outlined a forceful set of policies for such schools.
When it comes to failing schools, Barber expresses impatience. When a public school is failing -- not just going through a rough patch, but also systematically failing to educate its students -- there is only one question the authorities should consider: "How do I get these children a good education as fast as possible?"
"Once you have the answer to that question, you just do it," he said. "If it's close the school, you close it and move the children into a better one. If there are no better schools nearby, close it and replace it with another on the same site. But you do whatever it takes."
If Barber uses forceful language as he recalls his days as a powerful official in the Blair government, in his role as a McKinsey partner he speaks more cautiously, noting the need to respect clients' confidentiality, and perhaps in deference to the McKinsey official sitting in on the interview.
Despite his new corporate personality, however, Barber said he believes his role is still pushing for better schools. When a hotel manager, attracted by the presence of a news photographer, asked Barber to identify himself, he responded: "I'm an education reformer and this is the New York Times."