I may be wrong here, but those workers on very high salaries working in the city probably are going to live close to where they work partly as they can afford it and partly because if they work very long hours they can’t afford to waste too much time commuting.
Not necessarily. Higher salary often means older, with kids, and you've moved out of London for more space etc. What you can "afford" is the hefty season ticket from the Home Counties, not necessarily being close to the office.