IT HAPPENED IN A FLASH. ENGLAND'S Prince William and a few other boys were larking around on the putting green of the exclusive Ludgrove School, in Wokingham, on Monday, June 3, when, says a witness, ''one lad started swinging a putter around his head. William happened to be in the way.'' Knocked to the ground, with blood seeping from a cut on his forehead, the Prince, who turns 9 on June 21, fought back tears while his Royal Protection Squad detective ran to a phone to put ''Operation Prince,'' the palace's prearranged emergency plan, into action.

As the boy was rushed in a police car to the Royal Berkshire Hospital in nearby Reading, Princess Diana, after an immediate telephone call from headmaster Gerald Barber, jumped behind the wheel of her green Jaguar to speed from Kensington Palace to the hospital 36 miles away. Prince Charles, alerted in Highgrove, the family's country estate where he has been living apart from his family during the work week, was driven to the hospital in his blue Aston Martin.

As the boy was wheeled in for a CAT scan, Charles and Di ''were walking behind his stretcher, reassuring him,'' says eyewitness Sarah Prince, a 14- year-old schoolgirl. Transferred later in the day to London's Great Ormond Street Hospital, a ''brave, chatty and chirpy'' William, according to a palace spokesman, rode in an ambulance with his mother. Charles followed in his car.

Diagnosed as having a depressed fracture of the skull (a slight indentation of the bone) on the left forehead, William underwent a 70-minute operation to push out the dent and check for bone splinters and brain lacerations. Neurosurgeon Richard Hayward declared the procedure a ''complete success'' with little chance of the possible frightening complications in such cases: epilepsy and infection leading to meningitis. Diana spent two nights at the hospital and took Wills home on Wednesday.

It might have been a moment for Charles and Diana to lend each other comfort and support. But even before the operation began, at 8:40 P.M., Charles was on his way to keep a quasi-official royal engagement planned months ago: attending a performance of Tosca at the Royal Opera House with Environment Secretary Michael Heseltine and Agricultural Minister John Gummer. Arriving after the first act, Charles assured his guests that the boy's condition was ''not too bad,'' and after the performance traveled with them by night train to North Yorkshire for an environmental conference. He kept in touch by phone and visited Wills's bedside for 42 minutes the next evening before going on to what the palace called a ''private engagement.''

The public -- and the press -- were appalled by Charles's curious choice of priorities. WHAT KIND OF A DAD ARE YOU? shrieked a headline in the Sun. Jean Rook in the Daily Express wondered, ''What sort of father of an eight-year-old boy, nearly brained by a golf club, leaves the hospital before knowing the outcome for a night at the opera?''

Wills's mishap was only the latest in a series of incidents that have led the British public to question the paternal warmth of a man they once thought sensitive, but who now seems more concerned with the environment, architecture and polo than with spending time with his children.

In April, Charles returned from an official visit to Brazil and headed straight to the polo fields. Last month, he went directly from the Prague airport to a painting holiday in Italy, while Diana went home to her boys. Perhaps slightly chastened by attacks in the tabloid press, Charles flew from New Delhi to the Scilly Isles off the coast of England to be photographed riding bicycles with the boys on May 26, but left less than 24 hours later for a polo match in Gloucestershire. Complained columnist Rook: Charles ''is beginning to treat his sons like well-fed pets who know their place in the world of their utterly self-involved parent. Certainly it must hurt William and Harry to see their father more often on TV than in the flesh.''

In fact, says a source close to the family, ''Charles is apt to toss his polo schedule on the desk at planning sessions and ask that his business and family duties be scheduled around that.'' Diana, by contrast, plans her professional schedule around the school calendar and has never failed to collect William personally for his weekends off.

Even in a country where absentee parenting is commonplace among the aristocracy, Charles's paternal malfeasance has raised eyebrows. For the past nine months, his reputation as a delinquent dad has gone from bad to worse. He put in only a token appearance to say farewell to William when he went off to boarding school for the first time last September. At a holiday break in October, William raced happily into his father's palace study in London, only to find it empty. He burst into tears. After a terse phone call from Diana to her husband at Balmoral in Scotland, Charles faxed the boy a welcome-home letter.

At Christmas, Diana alone heard Harry's solo at the school Christmas concert. Over the Easter break, Diana and the boys were on their own again, except for a brief appearance with Charles at church. One day the three of them went to an amusement park, while Charles attended a horse meet; then Charles entertained friends at Sandringham and Balmoral, while Diana took the boys skiing in Austria. When Harry had a school break at the end of May, Diana alone took him to visit a Royal Air Force base and a wild-animal park.

Nobody knows exactly how many -- or how few -- days Charles has spent with his children in the last year or even whether he is comfortable with his kids. One close friend maintains that ''when he does see the boys, he's all over them. But then he might not choose to see them again for a month or so.''

That is the case according to Andrew Jacques, a former security guard at the Waleses' country home who became so bored with gate-watching that he quit to become an insurance salesman. Jacques told the tabloid The Sun that when the boys are at Highgrove, they routinely spend their weekends playing and riding, while Charles rarely leaves his walled garden (no children allowed) or the private dressing room where he has installed his brass bed from Kensington Palace.

Diana, after spending an hour phoning London friends, sleeps alone in the master bedroom. By her bedside, along with copies of Vogue and Country Life, says Jacques, there is a ''well-thumbed'' marriage advice manual.

To be fair, most of Charles's sins are those of omission. ''There's a certain kind of Englishman who doesn't take a lot of interest in his sons until they're able to kick a rugby ball, or, in his case, swing a polo mallet,'' says royals author Anthony Holden. ''The only public sign of affection Charles has shown was last year when he saw the boys playing a makeshift game of horseless polo. He called them over and patted them on the head. Charles does begin to look increasingly like that rather disappointing, repressed, uptight Englishman.''

In spite of an absentee father and the strains in their parents' marriage, the little princes seem nearly always resilient. William, who is second in line for the throne, has been in training for the job all his young life. He adores uniforms, loves riding and has already learned the rudiments of soccer, cricket, hunting, fishing and shooting, although last week's incident might put him off golf. Extremely well-mannered, he carried out his first royal engagement for the ''family firm'' in March -- unveiling a plaque with princely finesse.

A bright but hardly brilliant student, William got off to a lonesome start at Ludgrove, which had been chosen for him because of its academic standards, but seems to be adjusting well to sharing a room with four other boys. The golf-putter incident, says a Ludgrove spokesman, ''was not a fight, but an accident. He is a very-much-liked boy here.'' Angelic, however, he is not. The private William, says a knowing source, ''has much more of an image of himself than Harry, and therefore he's more worried about making a fool of himself. He is sensitive, temperamental and spoiled. He realizes that people defer to him, and even at his age he uses that.''

Ever mischievous, Wills was once photographed trying to pinch a comely teacher's bottom. Last August at Balmoral, he gave the security staff fits when he mounted his pony and rode off alone for a half-hour lark. After that episode, he was literally plugged into the security system and now carries an electronic homing device. But he can use that self-confidence well. As a surprise treat, he once reserved a table for his mother at San Lorenzo, her favorite restaurant.

Harry, 6, and third in line to the throne, is ''a happy-go-lucky character, and nothing seems to bother him,'' says a family friend. Like his big brother, he adores horses and soccer and is learning cricket as well. A day student at Wetherby, a posh London pre-prep school, he broke schedule last Tuesday to be his big brother's first postsurgery visitor at the hospital.

Royal sibling competition is as prevalent as the sibling revelry. ''There's a certain amount of rivalry between the boys, but no bickering,'' says one royal watcher. ''They are very good friends and have a close, healthy relationship.'' Of late, William has taken a shine to his cousin, Princess Margaret's son, Viscount Linley, 29. And both boys feel close to their bodyguard Ken Wharf, who is in his mid-30s. It was Wharf who comforted Wills when he burst into tears on the Austrian ski slopes last April because he was frustrated by a cold and the difficulty he was having keeping up with his little brother.

Charles and Diana clearly have different ideas on what family life should be. Though Diana's parents separated when she was 6 and later married different partners, her childhood was a relative idyll of cozy familial walks and picnics, frequent visits to the family's seaside cabin in Norfolk and festive birthday parties. She tries to provide the same for her children. Childhood for Charles, on the other hand, was a quick-march of pomp, circumstance, discipline and the stiffest of upper lips. He rarely saw either of his parents, who frequently traveled together on official business, and by slow boat at that. Charles, then, may well see nothing negligent or unusual about his behavior. Says a source close to the family: ''Charles is treating William pretty much the same way his own father, Philip, treated Charles.''

Though Diana has always been so solicitous of her boys that she could hardly do more to compensate for Charles's absences, she has taken one telling step in the last year. She has reportedly subjected herself to riding lessons for the sake of the children. Terrified of the saddle since she was thrown at age 5, she would never ride with the horse-loving Charles, even in the early days of their marriage.

What sort of damage, if any, is Charles's neglect apt to do to his children? Respected British psychologist and author Dr. David Lewis warns against comparing the Waleses to any ordinary family. ''These are not going to be normal children,'' he says, ''because this family is in a completely different ball game.'' The royal family, he says, ''are amazingly arrogant people.'' If William is temperamental and willful, says Lewis, ''this is the perfect description of a future monarch of this country. They are the characteristics they're expected to have. You could argue that William is being well-groomed in the traditional way.''

If that's the case, Charles and his sons are merely trapped in a pattern that has nothing to do with the '90s ideal of fatherhood, but has been part of the royal family fabric for generations. None of the three -- Charles, William or Harry -- has ever known anything different, or probably ever will. Dr. Ronald Levant, author of Between Father and Child and the former director of Boston University's Fatherhood Project, believes the principal problem with absentee fathers is that ''when ((the sons of such fathers)) grow up, they have trouble forming intimate relationships with their wives and children, and will repeat the experience with their own children, whether they like it or not.''

But, Levant adds, ''all kids really need is one adult who's absolutely nuts about them.'' And that, in the person of their doting mother, William and Harry certainly have.

People Magazine June 17, 1991