It's no secret that the Queen had a favourite breed of dog - she owned more than 30 corgis during her reign and they often joined her on trips across the UK and abroad. Her Majesty owned her first corgi at the age of seven in 1933, and went on to treasure pets for the next eight decades of her life.
During the 1980s, Queen Elizabeth II hired animal psychologist, Dr Roger Mugford, to help control her 11 pet dogs. The mischievous corgis had formed a pack at Buckingham Palace and would often play up - though Roger believed it was very common for a large group of animals.
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"The Queen… had several dogs, too many dogs, and they were fighting one another," Roger explained in an interview with CNN on Tuesday.
At the time, she had nine corgis and two dorgis - a cross between a dachshund and corgi - and needed help with "pack management".
Her dogs were known to go to the bathroom on the carpet, playfight one another and nip at guests.
They even had a small obsession with biting the guardsmen outside the palace, as the noise of stomping feet reminded them of "sheep being herded".
"The Queen herself is a very capable dog trainer, she didn't need a dog trainer," Roger explained.
"But as a PhD psychologist, I'm looking at what makes dogs tick and how they interact with humans."
Roger worked on building the dogs' relationships with humans and was able to get the Queen's corgis under control.
Then he spent the coming years working for the Royal Family as an animal behaviourist and trainer.
He noted the Queen had a "very, very powerful influence" over her pack and was a "hands-on" owner.
Roger believed Her Majesty found a great deal of comfort in her pets and always had a "good way with dogs".
"I think if it was the Queen on her own, she would have coped very well," he said.
The Queen's relationship with her corgis was different to that of a typical dog owner, as her wider staff and family helped care for them while she was away.
Though Roger said the "worst fights occurred when she was not present", which showed a lot about her character.
Her Majesty owned at least one corgi at any given time between the years 1933 and 2018, when the last surviving member of the royal corgi family, Willow, died.
Beloved Willow was put to sleep at Windsor Castle in April 2018 after falling ill of a 'cancer-related illness'.
The Queen was heartbroken over Willow's death but did not want her canine companion, who was almost 15, to suffer.
"She has mourned every one of her corgis over the years, but she has been more upset about Willow's death than any of them," a Buckingham Palace source told the Daily Mail.
"It is probably because Willow was the last link to her parents and a pastime that goes back to her own childhood."
Willow is thought to be buried in the castle grounds, along with all of the Queen's pets in a secluded area of the 20,000-acre Sandringham estate.
Leading up to Willow's death, the Queen made a touching sacrifice to no longer breed corgis.
"She didn't want to leave any young dog behind. She wanted to put an end to it," royal aide, Monty Roberts, told Vanity Fair magazine in 2015.
He added: "I have no right to try to force her into continuing to bring on puppies if she doesn't want to."
In the Queen's final years, she was gifted two corgis by her son, Prince Andrew, and his family.
Following her death, the sweet dogs, Sandy and Muick, will move in with the Duke of York and his ex-wife - which Roger believes is a positive decision, and says they will adjust well.
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