Activism, in a general sense, can be described as involvement in action to bring about change, be it social, political, environmental, or other change. This action is in support of or opposition to one side of a controversial argument.
There are many different forms of activism; a select list follows.
... Yorkshire
Museum of Rail Travel[?], Keighley and Worth Valley Railway
National Museum of Photography, Film and Television, Bradford
Royal Armouries Museum[?], ...