Political parties in the UK do in fact (in my own personal experience) impose some form of test on those wishing to seek election. I well remember how I almost blew one interview by a regional party selection panel by repsonding to a comment about the cobbles on the beach in Scarborough, saying the beach was sandy. The commenter was referring to small fishing vessels called cobbles!. Fortunagtely I did pass that hurdle but I then had to face constituency panels and, ultimately, a general meeting of constituency party members in competition with other potential candidates.