The British Royal Family has been one of the most popular and secretive families in the world since then. While the family is now more open to the public, things back then were different, especially during the time when Britain was in the middle of a "constitutional crisis."

In 1936, King Edward VIII became the King of the British Monarchy following the death of his father, King George V. While many individuals saw him as fit for his role at first, there was a change in tune of the dynamic a few months after. This was when the American divorcee, Wallis Simpson entered the bigger picture.

According to Express UK, the King of the British Royal Family made his plans known to the government, notably to the Prime Minister, that he will marry Ms Simpson no matter what costs were, even if abdication was necessary. But, considering that the "love" of his life was twice divorced and a non-royal, this was unacceptable.

Aside from the plans of marrying the American divorcee, there were also speculations that King Edward VIII was inclining toward the fascist movements across Europe. This is why his Prime Minister, Stanley Baldwin reportedly proposed to his circle and the director of MI5, Sir Vernon Kell, to conduct close surveillance toward the King of the British Royal Family and his partner, Wallis Simpson.

Speaking to History Extra, intelligence historian and expert, Rory Cormac and Spying On The Royal director, Paul Elston revealed some of the essential details of the controversial MI5 operation. It was said that these details were "unearthed" from sensitive documents dating more than 80 years ago.

The experts reportedly shared that the founder and first director of MI5, Sir Vernon Kell was hesitant at first when PM Stanley Baldwin brought the proposal of "spying" on the British Royal Family. However, upon laying all the concerns of the parliament, the operation started and went on for months.

The documents revealed that several surveillance operations were conducted to follow King Edward VIII and Wallis Simpson's day-to-day activities. In fact, there were even documents, as well, detailing some of King George VI's conversations with his brother, who later abdicated.

The operations reportedly included personal or "human surveillance," which involved following the royals and surveilling them while inside their homes. It was even shared that their bodyguards from the Special Branch were also in on the surveillance.

Aside from this, the "signal surveillance" was also conducted, which mainly involved "phone tapping." So, most of their conversations were recorded and filed in the unearthed documents.

While this may seem too sensitive and "intrusive," the experts noted that everything was done legally. Whether the surveillance itself was good or bad, it was understandable why the MI5 director and the Prime Minister conducted the surveillance toward the British Royal Family as they all saw an apparent constitutional crisis during King Edward VIII's short-lived reign.