The Queen is to send a private message of condolence to Queen Margrethe of Denmark following the death of Prince Henrik of Denmark.
French born Prince Henrik - the husband of the Danish Queen - died in his sleep on Tuesday at the age of 83.
The Queen is said to be close to Queen Margrethe.
In 2012, Margrethe revealed how she had always "admired" her British counterpart and that she has helped influence herself as a queen after watching how dedicated she was to her nation.
Buckingham Palace confirmed the monarch would be sending her condolences.
Henrik, who publicly vented his frustration at not being the social equal of his wife or their son, was made prince consort when Margrethe acceded to the throne in 1972.
The jovial prince was known for being frank and forthright.
A statement on the Danish royal house's website said the prince died in his sleep at the palace late on Tuesday, with the queen and their two sons at his side.
The palace said last week that his health had "seriously worsened" and that Olympic official Crown Prince Frederik was rushing home from the Winter Games in South Korea.
Prince Henrik was diagnosed with dementia last September and was earlier this year hospitalised in Copenhagen for a lung infection.