In a new interview with Stylist magazine, the author explained how she spotted parallels between the way the duchess is scrutinised in the media and the royal's late mother-in-law.
"Look at how certain parts of the press report on someone like Meghan Markle and what she does," Blackman stated.
"The barrage of abuse that Meghan is getting... it's kind of like she's damned with certain parts of the media, no matter what she does."
The author of the Noughts & Crosses book series outlined how the incessant scrutiny of the Duchess reminded her of "the way the press hounded" Princess Diana.
"I watch what's going on with Meghan and I think, 'This is along the same lines, but worse'," Blackman said.
"Meghan could wear a one-shouldered dress, two-shouldered, a boat neck or whatever, and the media would say it's not appropriate, because what they are saying basically is that she shouldn't be in the royal family."
In August 2017, the Dukes of Cambridge and Sussex opened up in BBC documentary Diana, 7 Days about the way in which the paparazzi "harassed" their mother prior to her death.
Prince William stated that if Princess Diana had been treated the same way in this day and age, people would have found it "utterly appalling".
Blackman spoke to Stylist about the treatment of Meghan in light of the release of her latest novel Crossfire, the fifth book in the Noughts & Crosses series.
The writer took inspiration from the current political climate when penning her novel, explaining that she wanted to explore the "naked ambition" of politicians.
11 of Meghan Markle's best feminist quotes
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On Sunday 4 August, Meghan celebrated her 38th birthday.
Her husband, the Duke of Sussex, led the celebratory birthday messages on social media, writing in an Instagram caption: "'Happy Birthday to my amazing wife. Thank you for joining me on this adventure!’ – Love, H.”
In July, it was announced that the Duchess of Sussex is launching a clothing line to support unemployed women through charity Smart Works.
Revealed in the September issue of British Vogue, which the duchess guest edited, the capsule collection has been created in collaborated with Marks & Spencer, Jigsaw, John Lewis & Partners and fashion designer Misha Nonoo. It will launch later this year.
For all the latest news on Meghan Markle, click here.
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