Queen Elizabeth II and Prince Philip have been married for almost 62 years, and during that time their relationship has had its share of ups and downs.
And according to a royal expert, there was one moment when the Duke of Edinburgh made a comment to the queen that shocked her so much, "she flushed scarlet".
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Ingrid Seward, who is editor in chief of Majesty magazine, revealed that an incident which left the queen "flushed" is said to have taken place when Philip walked past his wife’s dressing room.
Speaking on the UK documentary Secrets of Royal Dressmakers, Ingrid told of how she'd learned of the occurrence from royal designer Ian Thomas.
She said: “When he was doing the hem, Prince Philip walked through the Queen’s dressing room and said ‘hmmm, nice dress’.
“The Queen flushed scarlet. I always remember him telling me that story.
“She was just so thrilled to get the compliment from her husband,” she revealed.
According to another royal insider, the fact that the couple don't share a bedroom could have kept their marriage strong for so many years.
Lady Pamela Hicks, a cousin of Prince Philip, told royal author Sally Bedel Smith that the couple had connected bedrooms, as opposed to sharing a master suite.
"In England, the upper class always have had separate bedrooms," she explained, adding, "You don’t want to be bothered with snoring or someone flinging a leg around."
"Then when you are feeling cosy you share your room sometimes. It is lovely to be able to choose."