1. When you die, you would rather someone else decided what will happen to your property, possessions and assets.
2. You don’t particularly like your family and would like to make things that much more difficult for them in the event of your death.
3. You are concerned about the size of Britain’s deficit and want to make sure that the tax man takes as large a slice as possible from your estate in order to help reduce it. Very commendable. If only everyone else showed such a selfless spirit then public finances might not be in quite such a pickle.