Prince Harry and Meghan Markle surprised palace aides with their "highly ironic" decision to give their two children royal titles this week, an expert told Fox News Digital. 

"It appears that with one decisive stroke, she and Harry declared that their children would be prince and princess, basically making the king's decision for him," Christopher Andersen, author of the "The King: The Life of Charles III," said a day after the couple first referred to their daughter as Princess Lilibet in her christening announcement.  

The celebration for the 21-month-old was confirmed Wednesday. She turns 2 in June. 

"I can confirm that Princess Lilibet Diana was christened on Friday, March 3, by the bishop in the Episcopal Diocese of Los Angeles, the Rev John Taylor," a spokesperson for the Duke and Duchess of Sussex told Fox News Digital in a statement at the time.

PRINCE HARRY DESCRIBES THE REST OF HIS LIFE IN FIVE WORDS AMID 'SPARE' FALLOUT: 'FREEDOM'

Harry and Meghan holding Archie as a baby

One expert called Prince Harry and Meghan Markle's decision to give their children royal titles "highly ironic" given that they are no longer senior working royals.  (Dominic Lipinski/WPA Pool/Getty Images)

Andersen noted that "Charles has been dragging his feet on this one for six months now, and frankly, it did seem quite possible the titles might never be forthcoming if it were left entirely up to the palace."

On Thursday, the royal family's website was updated for the line of succession to include Prince Archie of Sussex and Princess Lilibet of Sussex, listed right after their father, the Duke of Sussex.

MEGHAN MARKLE, PRINCE HARRY'S DAUGHTER PRINCESS LILIBET DIANA CHRISTENED IN CALIFORNIA; ROYAL FAMILY A NO-SHOW 

"The largely faceless courtiers who run the monarchy — Diana used to call them the ‘men in gray’ — were clearly taken by surprise and none too happy that they were placed in the awkward position of having to update the royal website, and quickly," Andersen added.

Princess Lilibet, 1, and her older brother Prince Archie, 3, earned the right to their royal titles once their grandfather King Charles III acceded to the throne last year. 

The Duke and Duchess of Sussex shared the first photo of daughter Lilibet smiling in a blue dress with a white bow in her bright red hair

Lilibet and Archie's titles were changed to prince and princess on the royal family's website after the 1-year-old was referred to as princess in Harry and Markle's announcement of her christening.  (Misan Harriman)

"To put this all in context, it is worth noting that Princess Anne, the King's sister, refrained from giving her two children titles," Andersen said. "Similarly, the king's brother, Prince Edward, made the decision not to give his two children the HRH status. 

"It was obviously more important to Harry and Meghan that Archie and Lilibet get the full treatment, which seems highly ironic since the Sussexes are no longer working royals, live half a world away and spend a great deal of time lobbing grenades over palace walls."

He added that Harry and Meghan are in a "unique position" after stepping down as senior royals in 2020 and moving to California. 

"Like any parents, they want to see their children get what they feel is rightfully theirs. They are still resentful for having been sidelined as ‘lesser royals,’ and that goes double for their kids," he said, adding the palace was "hardly in a position to deny Archie and Lilibet titles once the Sussexes' declaration was made." 

Princess Anne smiling

Princess Anne didn't give her two children titles.  (Getty Images)

Andersen wondered if Harry and Markle's declaration suggests they plan to attend Charles’ coronation in May "perhaps even with their children."

"They have been invited, of course, but now it's more up in the air than ever," Andersen said. "The truth is, Charles may be quite upset that the Sussexes seem to have taken matters into their own hands once again. I'm sure William is not pleased. And all that just adds fuel to simmering resentments between the two camps."

The palace is reportedly planning for the duke and duchess to attend the coronation, with logistical staffers including their names in the May 6 program. 

King Charles in green suit adorned with medals and chains sits in a royal chair next to a crown

King Charles III's coronation will be held May 6.  (Alastair Grant)

"Harry and Meghan are being factored into all of the planning … the cars, the seating plans, dining arrangements, everything," a source told the Daily Mail. "No one knows for certain whether this means they have definitely accepted. It could, of course, be just in case they do. But it’s clearly not a 'no.' The staff are certainly working on the expectation they are coming. These kind of arrangements have to be made well in advance." 

The couple has not yet publicly accepted or declined the invitation. 

CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTER

Last week, a spokesperson for Harry and Markle confirmed the couple has been invited. 

"I can confirm the duke has recently received email correspondence from His Majesty's office regarding the coronation," a spokesperson for the couple said, according to the BBC. "An immediate decision on whether the duke and duchess will attend will not be disclosed by us at this time." 

Meghan Markle with her family

Prince Harry and Meghan Markle always manage to "steal the spotlight" from the senior royals, one expert said.  (Getty Images)

Kinsey Schofield, host of the "To Di For Daily" podcast, told Fox News Digital her "biggest takeaway" from the announcement was that Harry and Markle "always seem to steal the spotlight on the same day that they know working members of the royal family are trying to push their causes or an event."

Lilibet's christening announcement fell on International Women’s Day. 

"On International Women’s Day, we received our very first tweet from Camilla, queen consort, and we saw Catherine, Princess of Wales, visit the Irish Guards in her toughest camo," Schofield said. Schofield called their behavior a "classic example of why the relationships between the Duke and Duchess of Sussex's household clashed with the rest of the palace when they were working members."

Meghan Markle and Prince Harry pose together for a photo at an event.

Meghan Markle and Prince Harry are officially the parents of a prince and princess. (Angela Weiss)

She said the Sussexes "do not respect or obey the pecking order. Instead of allowing Catherine's cause to shine ... it's the Harry and Meghan show." 

Schofield explained that the palace will only promote one event at a time to "ensure that the next big royal event covers all the front pages of the paper." 

Kate Middleton in camo jacket speaking with soldier

Kate Middleton visited the Irish Guards on the same day Harry and Meghan announced they were using prince and princess titles for their kids.  (Steve Reigate/WPA Pool)

CLICK HERE TO GET THE FOX NEWS APP

"Harry specifically worked within the royal fold long enough to have known that on International Women's Day the palace would have had a special initiative planned," Schofield added. "They didn't grasp the concept while they were working members, and they certainly don't care to respect it now."