More than 30 years ago, British tabloid reporter Andrew Morton launched his career as a biographer with an explosive portrait of his good friend Princess Diana. Since then, he has authored dishy and dramatic portraits of celebrities like Monica Lewinsky and Angelina Jolie, as well as a book on the wedding of William and Kate. For his latest project, Meghan Markle: A Hollywood Princess, Morton spoke with people who knew the soon-to-be-royal at every stage of her journey, from childhood activist to struggling actress to TV star to most Googled woman on the planet. Here, he shares his thoughts on the similarities (and differences) between Meghan and Di, how Harry feared it wouldn’t last and why Buckingham Palace may want to start importing avocados ASAP.

You famously wrote the 1992 biography Diana: Her True Story with the co-operation of the late Princess. Was Meghan Markle’s participation ever an option for this book?

No, not at all. This was always an independent biography, although the irony is, I ended up writing it in Meghan Markle Central, Pasadena, California, where my wife is from and where we spend half the year. It’s in the same area where Meghan went to school and did her first drama productions, where some of her old teachers live, old boyfriends. I was very well-placed and as a result I have a fairly good understanding of young Meghan.

In the book, you quote a childhood friend who says Meghan “wanted to be Diana 2.0” when she was young. It’s a great detail, and yet the current media compulsion to liken Meghan to Diana seems a little over the top, no?

I think the abiding similarity is that they both have some sort of moral compass, but definitely the comparisons can be overdrawn, and there are also huge differences. Meghan was never going to be Diana 2.0, she is Meghan 1.0. From a very young age, she was articulate, loved being on stage, loved any sort of attention, which is the total opposite of Diana. And Meghan was an activist early on — she organized demonstrations against the Gulf War, she protested sexist advertising. That’s not the kind of thing that Diana would have been thinking about at the same age. It’s notable that people who knew Meghan when she was young didn’t think she’d become an actress — they thought she’d go into politics.

Meghan Markle is not your typical British royal bride: She is American, biracial, divorced and older than Harry by three years. Which of these things is the biggest deal?

I think race. I think the seminal image [from the wedding] will be the Queen and Doria Ragland [Meghan’s mother], who is fourth generation from slaves. Meghan being biracial will start a conversation about racial policy in Britain and even within Buckingham Palace, where there is [currently] a modest number of people from ethnic backgrounds.

She also hasn’t shied away from identifying herself as a feminist. Is that something that sets off royal alarm bells?

I think what’s interesting there is what is essentially the Meghan Markle Paradox: A successful actress and humanitarian [who has campaigned for gender equality], but who we are talking about because she is marrying a man who is famous based on dint of birth. I think what’s interesting when you look at Meghan’s past life — her work as an activist, her work for World Vision and the United Nations — she is someone who is accustomed to making speeches and someone who comes to the royal family fully formed. She’s not some ingénue being taught the royal ropes. She’s a person who has lived her own life and will require a different type of handling as she enters a world where, as Diana once told me, they will spend an hour discussing who shot the last pheasant of the day.

The Australian feminist Germaine Greer recently told 60 Minutes that she thinks Meghan will “bolt” after getting a better sense of the limitations of the life she is signing on to. What do you think?

I think there is a general cynicism regarding the prospects of this marriage. I’ve never been asked by so many journalists, “Is it going to last?” But it’s based on a false premise. Despite what people seem to think, Meghan will not spend all of her time in the presence of the Queen. They come together for certain events, but they tend to live their own lives. Harry and Meghan will start a family, and I think they will travel and be a far more international family than William and Kate, who, as the future King and Queen, are quite domestic. Harry is sixth in line to the throne and there’s a kind of freedom since he does not [earn an income from the government]. As for Meghan, she has said herself that she is a very considered person. She’s no fool and she understands what she is giving up and what she is getting.

So there’s not truth to the tabloid narrative about how much trouble she’s having adjusting to royal life?

I think what she may find frustrating are the quotidian: How does she find a decent hot yoga studio in London? How does she find a ripe avocado?

Surely a royal can have her avocados shipped in.

It’s true, and it’s kind of a joke about her being such a California girl. Every problem can be solved. Although the yoga places in London really do leave a lot to be desired. The point is that Markle is quite a sophisticated person, whereas people might be surprised to learn that the royal family leads a pretty utilitarian existence. With food, they definitely eat to live, not live to eat, whereas Meghan is a foodie.

What can you tell us about the dynamic between Harry and Meghan that we don’t see from pouring over tabloid pictures.

I think the dynamic is that he is the supplicant and she’s the one who had a decision to make. I’m told by people at the palace that he is completely and utterly besotted with this woman. Without even needing to be told, you could see that he was on tenterhooks hoping that she wouldn’t walk away, because she was the one who had to accept his lifestyle, not the other way around. His previous relationships had ended because of the attention, which is, I’m sure, what impelled that very emotional statement issued on his behalf by Kensington Palace.

Your portrait of Meghan is extremely flattering, though there is certainly the implication that she is calculated and socially ambitious. Is that how you see her?

There is no question that she is socially ambitious and I think she’d be the first to admit that. I don’t see why the fact that she’s a consummate networker is seen as a negative. The takeaway that I have after all of the time I spent researching is that this is a woman who worked eight years to get a break in Hollywood. She was 30 [when she got her role on Suits], she was at the point where she would have been thinking, “Is all this worth it?” She gets her big break and she makes the most of it. I think that shows she has determination and endeavour to spare.

Having studied the royals for many years, do you have a favourite?

Well obviously Diana.

Tell me something surprising about the Queen.

You ask some bloody awful questions! No, I’m only joking. I would say that she finds wearing the crown very heavy.