getting up at 4am and getting a 5am train to London!? What is it, a 2-3hour commute then?! There's got to be a time where you've completely exceeded the work life balance, and I think 4-6hours of commuting must smash through that point!!
I live a couple of miles from work and still struggle to run mornings. I find lunch and evenings suit, as long as the evening run is done straight away when home, say, 5:30.
Having said this I often get up at 6am on a sunday to get out and run up to 16miles at 7am!
Now that feels like commitment!