Tensions were so bad that the mother of Princess Eugenie and Princess Beatrice did not attend the royal wedding of Prince William and Kate Middleton in 2011.
However, over the years things have cooled down considerably, Fergie even copped an invite to the royal wedding of Meghan Markle and Prince Harry in May last year.
On the podcast 'Pod Save the Queen', renowned body language expert Judi James claimed that Fergie looked “insecure” and “vulnerable” on the big day at St George’s Chapel, Windsor despite waving at the crowd.
James told the podcast: “Her body language I found very touching actually, she had to walk in by herself.
“She was doing these little baby waves and a slightly creeping walk.
"She was clearly doing a good act of lowering her own status, it was as though she was creeping in via the servants’ entrance."
James also commented that the treatment of Fergie was unnecessarily hostile, even if Fergie's wedding invite is a small step forward in mending her relationship with the royal family: “I thought that was a bit of a shame and it was unnecessary.
“I noticed that one of her daughters quite quickly said, ‘Where’s mum?’
“In a church that small, I think that was a bit mean.”
WATCH! Fergie opens up about the feud between Meghan and Kate!