The purpose of listing is to protect our built heritage. Spen Valley has over 100 Listed buildings, of which the Red House Gomersal and Oakwell Hall are Grade I, the highest ranking. To find all of them, see Historic England's website
A Listed building can't be altered or demolished without "Listed Building Consent" for which an application must be made to the council's planning department. Sometimes, Council permission to alter a Listed building is granted because otherwise there will be no use for it and it may not be maintained. The price of this approach is that many listed buildings have been significantly altered and in some cases spoiled to make them useable. Conversely, some owners have saved dilapidated buildings and restored them to a high standard. Good examples of this are Old Hall, the pub on New North Road Heckmondwike; the former Albion Inn on Knowler Hill Liversedge; and Lowfold Hall on Roberttown Lane. A nearby building Duxbury Hall was completely renovated by Marshalls Construction at the cost of losing some of its garden to 5 newbuild houses.
Although buildings can be listed as being of historic OR architectural interest, in practice it is mainly about architecture. For example in 2009 the Society tried to have the Shears Inn listed, in order to obstruct its demolition. Despite being steeped in history, Historic England would not list the inn because all the original "architecture" had been altered over time. Sadly, the Inn is again under threat, with a planning application lodged to demolish it and build houses on the site.
Another point relevant to Spen Valley's heritage is that the buildings which are saved are largely those of the church and of wealthy people. The lists of protected buildings have few examples of ordinary people's homes, because the cheaper building materials they used rarely survived the ravages of time. Finally, the "setting" of many listed buildings has been spoiled by new buildings which are too close.