If Alistair Carmichael, MP for Orkney and Shetland, can manage to go back to his constituency almost every week, why can't Ruth Kelly be arsed to visit her Bolton constituency as often?
Mr. Carmichael has a 1,400 mile round trip each week by train, plane and sometimes by boat, whilst Ms. Kelly would only have to do 440.
I think it has something to do with dedication to your job, and an interest in the people you serve. Mr. Carmichael's constituents should be proud of him. He has the longest and most difficult journey home, but still manages it. Perhaps it's because he actually lives in Orkney, and not in London.
This BBC article is a very interesting insight into Mr. Carmichael's dedication to job. Read it and learn.