It wasn't quite the sort of lesson Prince Charles had in mind. During a family holiday at Queen Elizabeth's estate at Balmoral, Scotland, Charles decided the time was right to begin teaching his boy Harry, who turns 4 this week, the fine art of angling. Leaving Princess Diana and brother William, 6, behind, father and son tramped off to the banks of the nearby River Dee in search of salmon. Once there, however, Charles concentrated more on his own fly-fishing than on educating his charge—which turned out to be a costly mistake.

The littler prince at first sat watching dutifully while Charles flogged the water. But, like any child his age, Harry soon grew squirmy and wriggled his way down the bank. Dad kept on casting, so Harry launched a rear-guard assault in hopes of catching his attention. After giving Charles's tartan kilt a couple of tentative tugs, a suddenly bold Harry lifted the hem and peered intently at the royal backside.

The Prince of Wales was not amused. "Charles looked so embarrassed," an estate worker later said. "He turned round, pulled the kilt down and gave his son an earful." After reclaiming his dignity, Charles went back to fishing, and Harry, now somewhat subdued, played quietly by himself. At teatime, their creel still empty, the two hiked hand-in-hand back to the castle.

The British press went wild over Harry's uncharacteristic high jinks. Quoth the Daily Express: "It wasn't long before the heir presumptive became very presumptive. And the heir apparent became rather more apparent than he had been." Indeed, the kilt incident provided the public with a rare glimpse of the more rambunctious side of Harry, who was once so shy that he couldn't bring himself to speak to his nursery-school teachers. The No. 3 in line for the British throne probably didn't pick up many fishing tips on this journey down to the riverside. And if he learned anything about what an Englishman wears under his kilt, he isn't saying.