Truly, there is much work to be done on improving national literacy. "Visitor's please sign in," instructs the clipboard on the reception desk of the Department for Education and Skills. No doubt the Secretary of State's previous guest was allowed to bypass this oddly apostrophised formality.
The Prince of Wales had been invited in by Ruth Kelly's predecessor, Charles Clarke, who lambasted the prince for his "very old-fashioned" view of education. By coincidence, the heir to the throne finally arrived in the middle of another schools row. Only this one had nothing to do with him.
Did Kelly show her visitor the white paper that could unseat Her Majesty's Prime Minister? "I took him through the proposals, and he found them very interesting," she says. Was he supportive? "I don't think I should put any comments in his mouth, but we had a really good and well-informed discussion."
If, as she implies, the document got a royal imprimatur, that is one of its few endorsements. Many teachers, unions and Labour MPs fear independently run state schools would mean back-door selection and more inequality. Tony Blair, determined to drive through his public service reforms, faces a rebellion that could force his resignation.
Among the opponents is Estelle Morris, the former education secretary, who calls the latest structural upheaval "one of the most contradictory documents ever produced by government". First it was billed as a boost for consumer power, then as a lever for equality. But, according to Morris, the new freedoms on offer are "precisely those most likely to hold back social justice".
"I just don't agree at all," Kelly says. "It's fundamentally to do with creating a more socially just society; about giving children who don't have opportunities at the moment a greater stake." The aim, she adds, is "greater investment, more teachers and support staff, better school discipline . . . and [improved] leadership".
It seems telling that Kelly's proposals are damned by another woman chosen, until her unforced resignation, to run the department closest to the Prime Minister's heart. Is this unsisterly of Morris? "She's entitled to write whatever she likes. I'm completely relaxed about it," Kelly says.
If her laugh sounds nervous, that is the only hint of strain. Kelly, now 37, came to this job as the youngest woman to join the cabinet. With four children under eight, she offered proof that a politician could leave her office, and red boxes, at 6.30pm. "That is becoming a little harder, but I do pretty well," she says.
The superwoman honeymoon was brief. An early speech was deemed patronising, an NUT leader called her "the worst education secretary since 1997", and some questioned her "spiritual support" from Opus Dei, the hardline Catholic movement made notorious by The Da Vinci Code. Her previous white paper, rejecting the Tomlinson plan to abolish GCSEs and A-levels, earned her more brickbats. ("Did you bottle it?" I ask, and she says: "Absolutely not. I am more convinced than ever I was right.")
Another white paper, another bust-up, but Kelly cannot be faulted on courage, or endurance. I ask if she relies on faith, and she says: "I'm quite a strong person, and faith is a key part of me, but I wouldn't be in this job if I wasn't able to deal with whatever hits me. I absolutely expect that people sometimes won't like me and what I'm doing. You just have to take people on and show you're serious about creating a fair society in which everyone can prosper."
More engaging and animated than her broadcast persona suggests, Kelly is clearly a determined juggler of home and work. There may be a faint stain of someone's breakfast yoghurt on her aqua-blue top, but I cannot be sure.
Though she is organised, her white paper is not a model of clarity. Schools will be encouraged (though not compelled) to be run by trusts, or to become self-governing. Local education authorities will be the commissioners, not the providers, while maintaining the old relationship with schools that don't opt out. New school providers will include "educational charities, faith groups and parents".
In particular, Blair has extolled parent power, despite fears that those with their own children's best interests at heart are the last people who should be in charge. The white paper specifies that "parents are able to set up new schools".
But now Kelly says this isn't the plan at all. "I think there are very, very few parents who will want to set up their own school," she says. "The white paper is not about . . . parents running schools. It's just not." Would she want to control her kids' school? "I certainly don't want to run it, and I don't think the teachers would like it either." The real idea, Kelly says, is that parents get more involved.
On to faith groups, which don't seem central, either, to Blair's revolution of provision. "We're not really talking about trust schools being able to adopt a religious character," Kelly says. So that leaves "organisations such as universities and educational foundations", among which Kelly has detected great enthusiasm.
"The Open University has linked up with Microsoft. They want to get involved in running a school, or more than one." Does she envisage a wider role for business? "Well, on a non-profit-making basis, where they have expertise," she says. What about, for instance, Apple? "If they've got something to offer." Schools would be unbranded, Kelly stresses, which would seem to rule out the formation of St iPod's.
But where would she draw the line? McDonald's? I ask this question twice, expecting Kelly to declare her reforms a burger-free zone, but she says: "Well, it would depend if they were any good or not." So Waitrose, or Sainsbury, or any company setting up an educational trust could run a school? "I'm not getting into naming particular individuals who may or may not be interested, but if they're a serious player who can make a difference, then that's a help I think we should offer to our schools."
Kelly has denied there will be increased selection. Will she have to make that guarantee legally binding? "A self-governing school, by definition, sets its own admission criteria. That is not, or cannot be, a free-for-all. The [existing] code is on a statutory basis. There is some flexibility . . . but in no way can they select by ability. That is absolutely ruled out by law."
Such championing of the status quo seems unlikely to quell rebels' anxiety. Modernisers, conversely, deem the white paper too bland. Are all her opponents wrong? "There are advocates," Kelly says, but the example she cites - university vice-chancellors - sounds unlikely to sway a mutinous parliamentary party.
"We've got to have the courage of our convictions," Kelly says. But whose credo, exactly, is she defending? She denies, naturally, that her post is a poisoned chalice or that her speeches are reworked on Downing Street instructions. The Blairite schools minister Lord Adonis, far from being an irritant, is "a man of immense talent. We're friends, absolutely." Some think that Kelly, an "ambidextrous" minister favoured by Blair and Gordon Brown, has grown less close to the Chancellor, but she praises both men equally. When I ask if Brown will be the next prime minister, she says, without hesitation: "I'm sure he will be."
For now, though, the question is how bold Blair dare be in pushing plans that he has described variously as a "historic turning point" and "a continuation". Which is it? "It's both," says Kelly. Since she does not countenance Commons defeat, will she have to compromise? "We've got to listen to what people have to say and explain what's in the white paper. For example, these schools are not the same as grant-maintained schools, which are bribed out of the system to serve the elite."
That charge, levelled by David Cameron, may be mischievous but, as Jon Trickett wrote in last week's NS, Labour plans for independent state schools are strikingly similar to those rehearsed by Cameron in the Tory manifesto. "Cameron hasn't had an original thought as shadow education secretary. On special needs, which is the one area he's supposed to be passionate and expert about [Cameron has a disabled son], the only thing he's recommended is a moratorium. That shows the depth of the alternative policy he's proposing."
But Kelly has more tricky adversaries than Cameron. She will continue the charm offensive she and Blair have begun, stressing the need for "consultation" and "debate". There is, though, little hint yet of climbdown. A diluted bill would call Blair's leadership into question almost as starkly as defeat, and Kelly accepts that she, and he, are on trial.
"Yes, it's a big test. Absolutely. It's also the right test. I am absolutely clear about how important this white paper is to raising standards and meeting the needs of deprived children, and I will make this case." Does she think Blair's future is staked on the bill? "Well, it's a central manifesto commitment, and we've got to deliver." For all the hints of conciliation, this sounds like No Surrender.
While parts of the white paper make a better case for social justice than critics have allowed, the flip side of empowering parents is harsh sanctions. I ask if Kelly really thinks it right to fine those who fail to supervise their excluded children in school time. "If you had an eight-year-old child who had been temporarily excluded, would you leave them at home?" she says.
What about an unruly 16-year-old? "Oh, I see, a 16-year-old," she says, as if she has barely considered this possibility. She quickly points to "evidence that it works" and less punitive measures, such as parenting classes, but her initial vagueness gives the impression that the measure was made in Downing Street.
Given all the confusion, does she blame herself for selling the white paper so badly at the outset? "We can always be better and do better. We could do better, we should do better, and we will do better in the future."
Will this mea culpa, on her behalf and Blair's, appease opponents? It seems unlikely. Nor is it clear whether many schools will want the freedoms on offer, or if the "trust" concept will take off. Kelly does not strike me as a cipher doing the Prime Minister's bidding. I think she is passionately committed to helping poorer children, though whether this is quite the aid package she would have chosen to raise standards is another matter.
As she no doubt told Prince Charles, there is much work to be done on improving the nation's literacy. The fate of this white paper will determine whether Kelly is the one to do it.