Why have the fortunes of the English gentry degenerated?

The fortunes of the English gentry degenerated primary due to the reformation of the voting law. Initially, only land-owning gentry has the right to vote and they used their right to control the laws governing land ownership. When the voting law was reformed, the power of the gentry diminished, enabling non-gentry individuals to own land and create factories.

Since, the English gentry get their fortunes from leases on their lands used for farming, they were very affected when the people working on their lands opted to go to the city and become factory workers. Thereby decreasing their rental income.

Land taxes also increased and because some portion of the English gentry's land became idle and unproductive, they were not able to pay the increasing land taxes; forcing them to sell and dispose of their land to meet their tax obligations.