I don't think her resignation has anything to do with this. Check out this story...
http://www.timesonline.co.uk/article...058885,00.html
Another vacancy will be created this week when Karen Buck, a junior transport minister, is expected to quit her job. She said yesterday that she found her portfolio unsuited to her interests and wanted to work on the London Child Poverty Commission. She insisted that her resignation did not indicate any disillusionment with the government.