Meghan Markle and Prince Harry in 'anthrax scare' after letter containing white powder is sent to Kensington Palace

Since the infamous 2001 'anthrax attacks' in the United States, which killed five people, cases of hoax letters containing white powder have soared.

Earlier this month we learned that Vanessa Trump, Donald Trump Jr.'s wife, was evaluated in hospital after opening a letter containing white powder. The letter was addressed to her husband, but sent to their Sutton Place home. While Trump Jr. owns the residence, it is his mother-in-law that lives there.

Vanessa's mother gave the letter to Vanessa, who opened it and reported the substance she found. Ultimately it was found to be non-hazardous, but she and two others in the home were taken to the hospital as a precaution. But it's not just the US where these hoax attacks occur, as a similar letter was sent to both Meghan Markle and Prince Harry this month.

As you can imagine, security measures at Kensington Palace meant that the letter was intercepted before it reached them, but the couple have been informed of the incident. The discovery sparked a full security scare, with specialists brought in to analyze the material. Eventually, the results came back to reveal that the powder found was harmless.

Officers from the Met's Counter Terrorism command were called in when the letter was discovered on February 12 at Kensington Palace, one day before police found a package containing white powder had been sent to the Palace of Westminster. This second letter was sent to the office of Home Secretary Amber Rudd at the Houses of Parliament, and also contained an ultimately non-harmful substance.

Detectives are currently examining whether the two incidents are linked, though there have been no arrests so far in the investigation. Police are playing down the incident but Scotland Yard are still on high alert, with the Royal wedding of the couple due to commence in May.

As with any event of this scale, security is under constant scrutiny for potential threats during the ceremony. They are due to ride around a public route to greet crowds in their carriage after they are married at St George's Chapel on Saturday, May 19. The procession's route will take it through Castle Hill, High Street, Sheet Street, Kings Road, Albert Road, Long Walk, then Windsor Castle once more.

“They hope this short journey will provide an opportunity for more people to come together around Windsor and to enjoy the atmosphere of this special day,” Kensington Palace has stated.

This is the first security alert for Meghan, who has been assigned a security team from the Royalty and Specialist Protection Command, as well as having numerous security briefings involving how she should react in threatening situations.

While it is a rare occurrence, last October a suspect allegedly encouraged others to attack Prince George at school, warning that "even the Royal family will not be left alone". A 31-year-old man is due to face trial in connection with that particular threat in April.