There is a slight twist which enables this international "commute" however. His job has involved being on-site in with a client (in Scotland) for the last while, so even if he lived in London he would've been put up in accomodation anyway. So in reality his Spain->UK\UK->Spain round trip only happens once a week, but technically he's still doing an international commute :)
edit: Tidied up the rambling sentences
But for some context, West Hampstead is a fairly nice suburb on three different train and tube lines.
The rent for a one-bed flat is high as they are bid up by couples who are both earning. You are at a big disadvantage looking on your own. In my experience there is not much difference between prices for a one or two bed flat.
I think a big problem is the price of national rail transport into London from the commuter belt. It can easily cost £4,000 a year for a season ticket, wiping out most of the saving on rent or mortgage payments compared to living in the city.
Of course, network rail, the line operator, kicks back money for lateness but the strange rules of your franchise like paying out only on overall lateness and not considering a train that's too full for you to get on as late means they keep 90% of that back for themselves.
For most folks that's only part one of your commute, because few of us actually work where we get into the city. Typically this means getting on the underground for another 30 minutes, this time cattle is being a bit polite.
* Actually, the £4000 is what I would pay if I paid for a yearly ticket. Since I don't always work in London, I get month tickets. These cost £400 a month.
From a quick calculation my £4000 season ticket works out about £0.25/mile.