A time for first economic test.
Why would improvements in the quality and price of the commuter train services that bring people into London's mainline stations, such as Waterloo, from the surrounding suburbs please anyone who rents a property in central London? And why might the city's landlords be less enthusiastic about such improvements?
Improved public transport increases the alternatives to renting a place in the city.
When a 2 hour commute becomes a 1 hour commute, and people are able to get a seat on the train instead of standing, some decide they'd rather save money and move out of central London. Vacant apartments then appear on the market. Scarcity lessens, and rents fall.
Improving commuter services wouldn't just affect commuters; it would affect everyone involved in London's property market.
