Princess Diana would regularly break royal protocol when it come to a particular thing but there was one occasion which frustrated King Charles.

King Charles was once left frustrated after his former wife, Princess Diana, broke royal protocol, according to the late Princess of Wales herself.

The Royal Family have many rules in place that dictate their every move. One of these rules is that they traditionally only wear black at funerals or during periods of mourning.

It is even essential for them to always travel with a black outfit as a precautionary measure for the purposes of mourning.

Famously, the late Queen Elizabeth was touring Kenya in 1952 when she found out George VI died and she had become Queen.

But she had not packed a black outfit with her which meant a member of staff had to deliver one to wear as soon as she touched down in the UK.

However, the late Princess of Wales was known to regularly break this rule as she was pictured in black outfits several times.

Diana, labelled by many a style icon of her era, paved her own path when it came to fashion and one of her favourite items to wear was little black dresses, or LBDs, according to fashion designer Zandra Rhodes.

The late princess flaunted her black gowns on many occasions but there was one particular occassion before their marriage, which prompted Charles’s frustration.

During an interview for her biography in 1991, Diana revealed that ten years earlier, during a fun-raising concert and reception in aid of the Royal Opera House in March, her then-fiance was surprised at her choice of a dress.

The late princess raised eyebrows when she opted for an opulent black gown by David and Elizabeth Emanuel, the designers who ended up making her wedding dress a few months later in July 1981.

Diana recalled that at the event, when Charles saw her in her dress, he said: “Only people in mourning wear black!”

However, not even her future husband’s remark would stop her from wearing black on multiple occasions in the future.

The late Princess of Wales’s most famous LBD was the “revenge dress” she wore on June 29, 1994, at the Serpentine Ball in London, on the same day that the then Prince of Wales confessed on national television that he had been unfaithful to her.