Reason behind Andrew and Fergie's eyebrow-raising living arrangement

Despite divorcing in 1996, Andrew Mountbatten-Windsor raised eyebrows when he asked his ex-wife Sarah Ferguson to come and live with him after he was granted permission to live in the 30-bedroom Royal Lodge in Windsor in 2008.

But what was even more eyebrow-raising was that this arrangement continued for 18 years, only concluding when Andrew himself was kicked out and stripped of his royal titles.

Many have wondered what could have made the former Duke and Duchess of York, both 66, stick together even after going through a divorce.

Royal author Andrew Lownie, who penned the book Entitled: The Rise and Fall of the House of York, says that it was manageable because the pair did not have as much contact, it seemed.

"Sarah had her own set of apartments at the opposite end of the house, and although they did meet and speak on the phone, I don't think there was much contact," he wrote in the book, as per Hello!

"There was always this rather cynical idea that he was her calling-card for business and seeing members of the royal family."

READ MORE: When Tali Mason watched the movie Lion, she saw her life story on screen

READ MORE: Why Aussie couples are ditching decades-old wedding tradition

READ MORE: Incredible link that drove twin brothers and Sydney chefs Luke and Sam to success

Fergie has long called herself and Andrew the "happiest divorced couple in the world", doing so in an interview with USA Today where she explained, "We live in the same house, but then, it's a big house, so that's ok. But I think it's really good that we believe in compromise and communication and compassion. And family."

But Lownie says, "I can't see any future in that relationship now. They were kind of joined together – them against the world – and that's now clearly fractured.

"I think she feels that he's toxic and that he's going to destroy her branding opportunities, so it's time to go off on her own."

While Andrew has been "exiled" to Marsh Farm, in a converted farmhouse on the edge of his brother, King Charles III's Sandringham estate in Norfolk, Fergie's whereabouts are unknown.

She was last seen in April, a few months after Andrew's arrest in February, at a £2,000 ($3740) a night apartment at the Mayrlife wellness spa in Altaussee, Austria.

View gallery

Sarah Ferguson's life in pictures