While a heavily-pregnant Duchess of Cambridge made a surprise appearance at an Easter service in Windsor on Sunday, Meghan Markle and Prince Harry were notable absentees from the royal family outing.

It would have been the first Easter with her soon-to-be in-laws for Meghan, 36 – and the service was held at St George’s Chapel, where she will marry Harry, 33, on May 19 – but sources told various media outlets the engaged pair spent the day in private.

The no-show coincided with the release in UK newspapers The Sunday Times and The Sun of excerpts from a book on Meghan by Princess Diana’s biographer Andrew Morton.

And while the so-called ‘Markle Sparkle’ phenomenon has seen the former Suits star become an instant favourite in the UK, the new book calls her “calculated” and “very strategic” in the way she cultivates people.

In Meghan: A Hollywood Princess (to be released on April 17) Morton labels her “a networker to her fingertips” who froze out friends with the “Meghan chill” when she became famous.

A former friend reportedly describes her a “social climber” who is “controlling” and “fastidious”.

Morton claimed “perfectionist” actress Meghan rehearsed how to drink cups of tea ahead of her first 2017 meeting with Queen Elizabeth. He also divulged unflattering details of the end of the royal bride’s first marriage to Hollywood producer Trevor Engelson.

Meghan’s 2011 Jamaica wedding to Trevor Engelson was “so moving”, said a guest.

In the Times excerpt, the author claims Meghan and Engelson met at a ‘dive bar’ when she was just getting her showbiz start via a small sitcom role and a $US800-an-episode gig as a Deal or No Deal briefcase girl.

After their engagement, Meghan landed her breakout role as Rachel Zane on Suits, taking her to New York and Canada.

With Engelson based in Los Angeles, the couple thought “the sacrifice was going to be worth it”, Morton writes.

Their 2011 Caribbean wedding involved beach wheelbarrow races and parties, but soon “cracks began to appear”, writes Morton per The Sunday Times. His evidence? She took her Vitamix Blender to Toronto.

In mid-2013, Meghan’s announcement the marriage was over was “totally out of the blue” for Engelson, according to Morton.

“Trevor went from cherishing Meghan to, as one friend observed, ‘feeling like he was a piece of something stuck to the bottom of her shoe’,” claims the author.

The book also reports a ‘wealthy entrepreneur friend’ said the marriage ended so fast Meghan sent Engelson back her diamond wedding and engagement rings by registered mail.

Engleson wasn’t the only one relegated by “the rising star”, according to Morton.

Her LA friends “noticed the change in her”, he wrote, claiming she cancelled lunches with old pals in favour of friendships with “those who could develop her career”.

Harry and Meghan inspect a movie industry prosthetic foot at a Belfast science park on March 23. Photo: Getty

The book also appears to call into question Meghan’s claims in her post-engagement BBC interview with Harry that she “didn’t know much about him” before they met on a blind date in 2016.

Morton wrote that on the day of Diana’s September 1997 funeral, Meghan, then 16 and watching on TV, wept watching a 12-year-old Harry walking behind his mother’s coffin.

The Los Angeles schoolgirl became so intrigued by Diana she watched videos of her 1981 wedding to Prince Charles and kept a copy of Morton’s Diana: Her True Story on her bookshelf, says the author.

During a visit to London, she posed for a now-famous photo outside Buckingham Palace with friend Ninaki Priddy.

“She was always fascinated by the royal family,” Priddy told Morton.

“She wants to be Princess Diana 2.0.”