Sarah, Duchess of York has paid tribute to the Queen, saying that the monarch is her "greatest mentor" and has always believed in her.
The 61-year-old, who divorced the Duke of York in 1996, was speaking on the Tea with Twiggy podcast about her debut romance novel, Her Heart For a Compass.
READ: Sarah, Duchess of York shares sweet memory from Princess Eugenie's first day of nursery
WATCH: Sarah Ferguson credits the Queen as her 'greatest mentor' in emotional podcast
She said of her former mother-in-law: "My greatest mentor and… person who believes in me is the Queen – and has never faltered.
"I absolutely admire the incredible way Her Majesty is so modern… and how flexible, and how understanding, and how forgiving and how generous."
Sarah was pictured arriving at Balmoral Castle last week with her former husband, Prince Andrew, with whom she still resides at Royal Lodge in Windsor.
The Duchess reportedly had a strained relationship with her former father-in-law the Duke of Edinburgh, following her separation from Prince Andrew in 1992, and would only stay at Balmoral when Prince Philip wasn't in residence.
MORE: Princess Beatrice says having dyslexia is a 'gift' and any of her future children would be 'lucky' to have it
MORE: Princess Eugenie's husband Jack Brooksbank set for 'new job'
Sarah and Princess Beatrice with the Queen at Royal Ascot in 2018
Sarah also told model Twiggy, whose real name is Dame Lesley Lawson: "I think to myself that honestly my mother-in-law has been more of a mother to me than my mother.
"I absolutely think there is no greater mentor because, from a little girl to now, the consistency of Her Majesty has been a great honour, it’s a huge honour – makes me want to cry."
The Duchess's mother Susan Barrantes left her behind in the UK when she was 13 to start a new life in Argentina with polo player Hector Barrantes. She was killed in a car crash in 1998.
However, Sarah penned an extremely heartfelt letter to her mother in 2015, saying that she forgives her.
"It has been 17 years since you departed on your last drive from the farm in Argentina," wrote Sarah.
"There is not a day that doesn't go by when I wish I could pick up the telephone and tell you what I have been doing."
Make sure you never miss a ROYAL story! Sign up to our newsletter to get all of our celebrity, royal and lifestyle news delivered directly to your inbox.