25% for rent in London means you'll have a lot of money to spend. If you spend 25% of your salary of $2000 on rent on the countryside you'll live off $1500. If

25% for rent in London means you'll have a lot of money to spend. If you spend 25% of your salary of $2000 on rent on the countryside you'll live off $1500. If in the city you can make $5000 but spend 50%, you'll still have more, even after higher other costs in the city. Sounds like an extreme example but in the UK, London vs. countryside further North has those differences.