Wispa's death comes only a few months after Queen Elizabeth lost her corgi Willow, the last of the descendants of her first corgi Susan, which was gifted to her on her 18th birthday.
"The death of any of her corgis has always hit her hard and Whisper's was no different". It is not known what his cause of death was.
A source told the Daily Mail newspaper: "Whisper was a friendly chap and followed her everywhere".
Her Majesty chose to stop breeding corgis five years ago - apparently for two reasons.
The only thing that did change for the dog when it moved in with The Queen was the spelling of her name.
According to the Daily Mail, Whisper is understood to have fallen ill some weeks ago, but was well enough to travel back from Scotland to Windsor at the end of the Queen's summer break. Susan herself was a gift to the queen (who was then a princess) on her 18th birthday.
Britain's longest serving monarch has kept corgis since 1944 but stopped breeding them as she did not want to be outlived by her pets - which are said to be disliked by the rest of her family.
The last of the 91-year-old monarch's famous corgi pooches has reportedly died, leaving her with her two dorgis - dachshund and corgi crosses - called Candy and Vulcan.
He must have made quite an impression: The queen has reportedly had more than 30 of the dogs since 1945, though she chose to stop breeding them in 2015 according to the Daily Mail, for fear that she "might trip over and hurt herself".