I believe that the Parliamentary Whip is a threat to democracy. If you look at http://www.parliament.uk/about/mps-and-lords/principal/whips/ you will see what one does. Although I understand why they exist, surely the MPs are there to represent the people who voted for them and not the party they belong to.
The Parliamentary Whip should be abolished. If people belong to a part, it should be because they are ideologically in tune with the other members. This should guide their vote, not the threat of sanctions.