Let's start with Sweden. September 15th 1973 turned out to be a very important day for the Swedish monarchy. On that day, Gustaf VI Adolf died bringing to an end a 23 year reign and his crown passed to his grandson, Carl XVI Gustaf. On that same day, a little boy was born in the middle of the kingdom. Daniel Westling went on to marry Carl XVI Gustaf's daughter and heiress, Victoria, and father the future queen regnant of the country.
The King of Sweden and the boy born to be consort - Prince Daniel arrived on the day his future father in law acceded to the throne
Carl XVI Gustaf's queen will have to wait for her own 40th anniversary - the couple married in 1976. Her 40th anniversary will fall on June 19th 2016 which will also be Daniel's 6th wedding anniversary as he and Victoria married on the same date as the king and queen.
An official portrait of Crown Princess Victoria and Prince Daniel of Sweden
(photo copyright kungahuset.se)
This year is also a biggie for the new forty somethings in Sweden's neighbor, Norway. Crown Prince Haakon Magnus and his wife, Mette-Marit, both mark this big birthday in the summer. Haakon is now 40 having celebrated in style on July 20th with a massive party that started with the heir to the throne parachuting into the festivities. Mette-Marit is a year younger on paper for just a few more weeks until her celebrations on August 19th. Whether she tries a spot of sky diving to match hubby remains to be seen.
Back on terra firma - Haakon Magnus an Mette-Marit of Norway in a photo taken to mark their 40th birthday celebrations this summer
(photo Norwegian royal household)
Whether Mathilde of Belgium knew she would become queen when this year got underway, she was pretty certain that 2013 would be a biggie for her as she marked her own 40th birthday in January. Her own celebrations were slightly more low key with six official photographs and a stamp marking the occasion. But then an accession and a major 40th party might be a bit too much for any queen in one year.
Mathilde and her children in a photo taken to mark her 40th birthday on January 20th 2013 - six months later she would become Queen of the Belgians
After that we've got a wait for another 40th - and then it will be back to Sweden where Crown Princess Victoria is due to mark her big birthday in 2017.