For some time, I've believed that the problem with most political parties (or at least, the one I'm able to observe at close hand - Labour) is that the key relationship - between the political party and the people who are elected in their name - is broken.
Liberal democracy works very well if you have competent, independent minded people being put up to Parliament by a few political parties with broadly competing ideologies. The whole process of deliberation and legislation should, if this works, be optimised.
That's the theory, anyway. But this hasn't been the situation for some time now - and it's been getting a good deal worse. The current political crisis is, I believe, a symptom of this.
Because of the domination of the national agenda, and the sensitivity to the national media, a situation has been allowed to grow up in which the parties have been able to dominate the constituency parties, and have sought to parachute suitable candidates in.
Alongside this, in the 1980s, my own party went though a bout of turmoil where activists sought to deselect candidates on their policies (insisting they adopted policies that the voters wouldn't stomach) rather than on their abilities, their ability to interact at a local level, and their personal integrity.
The result is a slightly autistic and unaccountable political caste, answeralble only to small whithered political parties.