> You sound like the Golgafrinchans. If only "professionals" live in London, who cleans up after those professionals, serves them coffee, or does any of the other non-professional tasks that keep a city moving?
Commuters who live outside of London proper and commute in for work?
> Do you expect your £18Kpa hairdresser (or the minimum-wage junior that sweeps up the hair) to spend £5Kpa (after tax) getting to work, or would you prefer to have go to Northampton every couple of months to get your hair cut?
I'd expect the price of the service they are providing to rise until it justified either them commuting into the city or their living in the city. If development in the city is constrained, probably the former.
Commuters who live outside of London proper and commute in for work?
Cities aren't the same thing as planets.