Who they were
The youngest son of Chulalongkorn (Rama V), Prajadhipok was educated in England at Eton and Woolwich. He came to the throne in 1925 on the death of his elder brother Vajiravudh.
What they did
He inherited fiscal strain and responded with budget cuts, including officials’ salaries, during the Great Depression — commonly assessed as one trigger of the discontent that produced the revolution. He considered constitutional reform drafts before 1932 but did not enact them. When the People’s Party (Khana Ratsadon) seized Bangkok on June 24, 1932 while he was at Hua Hin, he accepted a constitution rather than resist, becoming Siam’s first constitutional king. Relations with the new regime then deteriorated over royal powers; the royalist Boworadet revolt of 1933 was crushed, and his involvement was never proven. He left for England in 1934 for medical treatment and abdicated on March 2, 1935, stating in his abdication statement that he was willing to surrender his powers to the people as a whole, but not to any single group.
Legacy
He lived quietly in England until his death in 1941. His abdication statement is one of the most quoted texts of Thai constitutional history. He was succeeded by his young nephew Ananda Mahidol (Rama VIII).