I don't know who compiles these credit lists, but they seem to suggest that Shelley, Fran and Mrs. H only appear in one episode of the series as opposed to every episode. As a result, the three main characters do not even appear on the main listing...just mentioned it as a point of curiosity.
shareVery slowly things are taking shape on IMDB for some older UK shows, but its still quite a mess..
shareYou have the option to update his appearances but it is a lengthy process due to the protocols involved.
It does seem strange that the show is named after him and as the main character he wasn't initially inserted into every episode at the top.
Remember,you don't have to be smart if you can pretend to be someone else who is...