A lot of it came to an end after World War I. Terrified by the idea of Bolshevism spreading westwards the UK government brought in the start of the social welfare system and paid for it with Income and Inheritance taxes.

Land became less of a guarantee of wealth and by World War II a number of the old estates had fallen into ruin. Meantime, family heads were having to cut off their wastrel sons.

Wait, wait, wait. The Drones are a very specific class of aristocratic younger sons. The older sons were being prepped for positions in running the estate, government, trade, the army etc. After those sons you had a bunch of sons who had no role, and lived idle lives on middling stipends.

At the time, open homosexuality was absolutely not tolerated. Campy is not the same as openly gay, but those who walked the line too closely would sometimes find themselves packed off to remote places and sometimes even married off under threat of being "cut off" - that is having their stipend withdrawn.