Short answers, pulled from the story.
George Allen & Unwin was formally established on the 4th of August 1914, when Stanley Unwin purchased a controlling interest in George Allen & Co. The predecessor firm, George Allen & Sons, had been founded in 1871 by George Allen with backing from John Ruskin.
Allen & Unwin published J. R. R. Tolkien's The Hobbit in 1937 and The Lord of the Rings in 1954-1955. The firm also published works by Bertrand Russell, Roald Dahl, Arthur Waley, Lancelot Hogben, and Thor Heyerdahl.
Allen & Unwin Australia became independent in July 1990 through a management buy-out after the UK parent firm, Unwin Hyman, was sold to HarperCollins. The Australian branch separated rather than being absorbed into the HarperCollins operation.
Rayner Unwin was Stanley Unwin's son and helped run George Allen & Unwin. He retired at the end of 1985, then returned as part-time chairman of Unwin Hyman before retiring again at the end of 1988. As the largest shareholder, he opposed the 1990 sale to HarperCollins, but the sale proceeded regardless.
Unwin Books was Allen & Unwin's paperback imprint launched in the 1960s. It published works on philosophy, politics, and literature, including titles relating to Marx, Trotsky, Freud, Zen Buddhism, and Tolkien, with the catalogue eventually numbering more than 80 titles.
In 2017, Allen & Unwin declined to publish Silent Invasion because of legal concerns that the book would be targeted by Beijing and its proxies in Australia. The decision drew widespread public attention to the pressures publishers can face over politically sensitive works.