Why did John Burdon Sanderson (J. B. S.) Haldane relocate to India as noted in the book, A Mathematician’s Apology?

John Burdon Sanderson (J. B. S.) Haldane, one of the most influential scientists of the early twentieth century, was well known for his left-leaning politics. Disillusioned with the state of Marxism after World War II, he moved to India, where he continued to conduct scientific research.