I think the way MP's should be held accountable is the seriousness of the morally wrong or criminal activity they have commited. The reason I think this is because if they have done something morally wrong there is no criminal activity it is just a promise they have broke. The way we as the general public can hold them accountable is if we do not vote for them and if they are the PM we can hold protests. The way we can hold them accountable if they have done criminal activity is if we take them to court because they are still average people but they are just in a position of power. We could also punish them by impeachment (like the process Donald Trump is going through) or we could make sure they do not become an MP again and rise through the ranks.