Inside Prince Andrew's decision to step down from royal duties: How the Queen reacted to his Epstein scandal

Queen Elizabeth is dealing with a royal scandal following her son, Prince Andrew, stepping down from his royal duties on Wednesday.

The 59-year-old Duke of York announced he will no longer be taking on his royal duties "for the foreseeable future" after making headlines due to his ties to disgraced financier Jeffrey Epstein. Prince Andrew spoke with the BBC last week in a televised interview that has been widely criticized, and denied he participated in underage sex with one of the late Epstein's alleged victims. ET spoke with royal expert Katie Nicholl on Thursday, who says that despite reports that the queen forced Prince Andrew out, sources tell her that ultimately, it was his choice to step down.

"My sources at Buckingham Palace are insisting that it was the duke's decision and that the statement reflects that," Nicholl tells ET. "He says in that, that it's his decision to step down with the queen's approval. ... Reading between the lines, it is my understanding that Andrew understood he had to go. It was made very clear to him in that meeting between him and the queen that he had no choice but to step down from royal duties."

"It must have been incredibly hard for the queen, his mother -- Andrew is widely regarded to be her favorite son -- but she recognized that there was a huge amount of damage being done to the monarchy," she continues. "He had no option, the queen had no option, but for Andrew to step back from royal duties."

Nicholl says Prince Andrew stepping down from royal duties doesn't mean he's getting "kicked out" of the royal family, and that senior palace aides tell her that he will still be standing with the royal family on the famous Buckingham Palace balcony at high-profile events like the Trooping the Colour parade. He will also still walk his daughter, Princess Beatrice, down the aisle at her upcoming wedding. Nicholl notes that although the scandal is hard for 93-year-old Queen Elizabeth, she is used to putting the monarchy before her personal feelings.

"The queen put on an incredibly brave face last night after leaving that meeting with Prince Andrew and telling him effectively that he had to step down," she says. "It is business as usual for the queen. What you have to remember is the queen has always put duty before self ... for the queen, it is upwards and onwards. For the queen, the most important thing is the unity of the monarchy. The reason that she and Prince Charles knew that Andrew had no alternative but to step down was to preserve the integrity of the monarchy."

Still, it has been an incredibly difficult year for the queen, given what the royal family has been through. Her husband, Prince Philip, was involved in a car crash in January, and Meghan Markle and Prince Harry have been candid about their struggles being in the public eye. Nicholl says the queen is pulling through the way that she has always handled difficult events.

"Her modus operandi is to group together," she says. "The royal family is like a herd in a moment of crisis, they come together. And the queen's mantra is never complain, and never explain. Keep on going, the show must go on."

In Prince Andrew's official statement on Wednesday, he said his Epstein scandal had become a "major disruption" to the royal family's work.

"It has become clear to me over the last few days that the circumstances relating to my former association with Jeffrey Epstein has become a major disruption to my family’s work and the valuable work going on in the many organizations and charities that I am proud to support," he said in his statement. "Therefore I have asked Her Majesty if I may step back from public duties for the foreseeable future, and she has given her permission."

"I continue to unequivocally regret my ill-judged association with Jeffrey Epstein," he continued. "His suicide has left many unanswered questions, particularly for his victims, and I deeply sympathize with everyone who has been affected and wants some form of closure. I can only hope that, in time, they will be able to rebuild their lives. Of course, I am willing to help any appropriate law enforcement agency with their investigations, if required."

On a happier note, Queen Elizabeth and 98-year-old Prince Philip recently celebrated their 72nd wedding anniversary and received well-wishes from Prince Harry, Meghan and more.