Prince William Once Twinned With Mom Princess Diana on Easter Sunday in the Cutest Throwback Photo

Princess Diana was well known for her love affair with fashion designer Catherine Walker's impeccably tailored designs. The British couturier was behind some of Diana's most iconic looks, and decades later, Kate Middleton would go on to favor the label, too. But Prince William once sported a Catherine Walker design for an important moment in his own life—his first time attending an Easter church service with the Royal Family.

The future king was just four years old when he joined parents Princess Diana and Prince Charles and the rest of the Royal Family for church at Windsor Castle's St. George's Chapel on Easter Sunday 1987. Diana didn't choose just any design for her son's big debut, dressing him in a pale blue Catherine Walker coat that was an adorable miniature version of her own Easter outfit.

Diana's double-breasted wool coat featured white trim and white buttons along with slanted pockets, but William's was designed in a slightly different style with a Peter Pan collar and straight pockets. The toddler added white ankle socks and black Mary Jane-style shoes to his look, while Princess Diana sported very '80s white pantyhose and coordinating white pumps with a matching scarf and blue-and-white hat.

Princess Anne's son, Peter Phillips—dressed in a very grown-up suit— held hands with his little cousin in the sweet photos from the day.

In one snap, Peter, Diana and Prince Charles are walking up the hill towards the castle when Prince William turned around and gave a cheeky wave and smile to photographers.

Prince Harry was too young to join the royals at church that year, going on to make his Easter debut in 1989. Harry, however, didn't experience the mother/son twinning moment William did for his first time at the service. Instead, the then-4-year-old wore a burgundy coat with shorts and knee socks while Diana attended church in a fuchsia and black coat over a matching spotted dress.

This year, Prince William and Princess Kate are skipping Easter with the royals, choosing to instead spend the holiday privately at their country house, Anmer Hall. The King, Queen Camilla and other members of the Royal Family will gather for church at St. George's Chapel, followed by a lavish Easter lunch, including plenty of high-end chocolates.