Sirindhorn was born on 2 April 1955, the third child of King Bhumibol and Queen Sirikit. As the royal couple has only one son, the Thai constitution was altered in 1974 to allow for female succession. This made Sirindhorn second-in-line to the throne (after Vajiralongkorn) until the birth of Princess Bajrakitiyabha in 1978. Air Chief Marshall Siddhi Savetsila, a member of the privy council, told a former U.S. ambassador in early 2010 that Sirindhorn could be named successor in the event of Vajiralongkorn's death, i.e., the crown prince's children, including Prince Dipangkorn, might be passed over