LONDON » Walter Bagehot, in his 1867 book, "The English Constitution," famously described the key to a lasting monarchy as mystery and obfuscation. "Above all things our royalty is to be reverenced, and if you begin to poke about it you cannot reverence it," he wrote. "Its mystery is its life. We must not let in daylight upon magic."

These days, however, the task is rather different: controlling the daylight to preserve, or restore, the magic. And if that requires a devious spin doctor, so be it.

But not too much daylight, please.

In a controversial decision, the BBC has postponed the scheduled broadcast of a documentary about how the royal family hired a public-relations professional to restore the reputation of Prince Charles after the 1997 death of Diana, Princess of Wales, and to help integrate into the royal household his then-lover, Camilla Parker Bowles, whom he later married, and who is now the Duchess of Cornwall.

The first part of a two-part documentary, "Reinventing the Royals," was supposed to be broadcast on Jan. 4, but the BBC has postponed it for an indefinite period "while a number of issues, including the use of archive footage, are resolved," the public broadcaster said in a statement.

But according to the RadioTimes, which broke the story, the BBC acted after "an intervention from lawyers known to represent senior members of the royal family, including the Prince of Wales and the Duchess of Cornwall."

The documentary focuses on Mark Bolland, a public-relations executive hired by Charles in 1996 as an assistant private secretary. Bolland served as the prince’s deputy private secretary from 1997-2002, then served as his public-relations consultant in 2003.

The documentary is presented by Steve Hewlett and was made without the cooperation of the royal family. It shows how Bolland took every opportunity to show Charles as a loving father and concerned single parent, while trying to win public acceptance for Parker Bowles.

The filmmaker reports that the campaign to integrate Parker Bowles into palace life was named "Operation Mrs. P.B.," and that Charles understood his standing with the British public had been deeply damaged by the death of Diana in a car accident in Paris and revelations of his relationship with Parker Bowles.

It also traces the deep suspicion of the news media by Prince William, his eldest son with Diana, to an incident in which he felt he had been "used to further his father’s interests" after news of his first private meeting with his future stepmother was leaked to the British tabloid The Sun, just 10 months after his mother’s death, when he was 15.

William wanted to know how it happened, although it later turned out to have been accidentally leaked by a staffer for Parker Bowles, according to Sandy Henney, who was press secretary to Charles when Diana died. In an interview for the documentary, she described the incident as a "defining moment" for William.

As a consequence, according to Hewlett, William became deeply wary of the press. "For William, protecting his privacy and that of his family has perhaps understandably become a virtual obsession," Hewlett wrote in an article for RadioTimes. But "in a new media age dominated by the Internet, with all the accompanying expectations of openness and transparency, there are real concerns, even within the royal household, over the sustainability of William’s approach."

Tom Bradby, a one-time royal correspondent and now ITV’s political editor, said that the princes never lost their disdain for the press. "William and Harry were very angry," he told Hewlett. "They thought that the media had hounded their mother to death. I don’t mean they vaguely thought that; they actually thought that’s what had happened."

Bolland created resentment among the palace staff, according to the documentary, while William and his brother, Prince Harry, referred to him as "Blackadder," after a television comedy starring Rowan Atkinson about a devious, scheming, cowardly opportunist close to the royals.

Henney is forthcoming in the documentary. Years before Diana’s death in a car accident in Paris, Charles "was getting some pretty virulent criticism: bad father, unloving husband," Henney said. "I think he was pretty hurt. If you’ve got a middle-aged balding man and a beautiful princess, it’s a no-brainer as to who is going to get the media coverage."

Relations between the royal family and the BBC, a public broadcast station dependent on licensing fees paid by nearly everyone in Britain with a television, have often been strained, especially during times of royal scandal. Their rift was on display in 2007, when the controller of BBC One resigned after the network showed a misleading trailer at a press launch in which it appeared that Queen Elizabeth II had walked out of a photo shoot after being asked to remove her crown.

In a statement about the delay, the BBC wrote: "The BBC is delaying broadcast of the documentary ‘Reinventing The Royals,’ due to be shown on BBC Two on Jan. 4, until later in the new year while a number of issues including the use of archive footage are resolved." Permission from the royal family to use such footage is normally granted without fuss.

A spokesman for Clarence House, where Charles and the duchess live, have denied asking that the program be pulled or postponed, though there were reports of detailed talks between the BBC and the royals throughout the year or so it took to make the documentary. "Scheduling of television programs is a matter for the broadcaster," the spokesman said.

Bolland, who now has his own public-relations firm, was unavailable for comment.

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