House Order of Successions
King Rama IX
H.R.H. Crown Prince Maha Vajiralongkorn (Son and the heir apparent of King Rama IX, the current king)
H.R.H. Princess Maha Chakri Sirindhorn, the second in line to the throne ad of December 5, 1977 since then. Her royal title in Thai language contains the word 'Crown Princess' which is almost equivalent to her brother. But in English language, she is styled 'Her Royal Highness' and is equivalent to the British title of The Princess Royal.
H.R.H Princess Chulabhorn Valailak (Youngest daughter of King Rama IX)