In our exit interviews we try to show the voices of MPs, so this is me reading into what we've heard in the past.
One big point we find in our surveys generally is that for MPs, the career ladder at Parliament is very strict. There are not many options, other than trying to get into cabinet. That's how you climb. That's how you are seen to accrue greater influence in policy-making, so everyone wants it, and of course there are limited spots. I think many MPs have a view that they have something to offer. Many of them do, but when it comes to decision-making in parties—I think this is universal across parties—a lot of decisions happen in opaque ways.
It kind of goes back to my point about nominations being a black box. As MPs, you don't really have a good idea as to what is being weighed in a decision made by your party leadership at all times.