There is nothing I can think of that would cause Drupal out of the box to redirect "programmes/something" to "programmes," assuming both are node paths. A bad path should return a 404 error. If "programmes" is the path for a view, it would take "something" as an argument, and finding no results it would use the default value for the argument, but that does not appear to be the case here.
What are your alias and redirection settings? For example, if you have Drupal set to keep and redirect old aliases, you'll have to delete the unwanted bad paths under URL Aliases or correct them under URL Redirects, depending on what you have installed. If you have it set to keep old aliases but do not have Path_Redirect installed, the old alias gets treated as canonical. Any newly created aliases will bring up the correct node, but the location in the browser bar will be the older one.
I would also investigate whether any global redirection is set on /membership*.