https://mitpress.mit.edu/9780262544283/nordenholts-million/

In this novel originally published in 1923, as denitrifying bacteria inimical to plant growth spreads around the world, toppling civilizations and threatening to wipe out humankind, the British plutocrat Nordenholt sets himself up as the benignant dictator of a ruthlessly efficient, entirely undemocratic, survivalist colony established in Scotland's Clyde Valley.