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 English Heritage'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; and Lowfold Hall on Roberttown Lane.
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 English Heritage would not list the inn as it said all the original "architecture" had been altered over time. Fortunately the new owners decided not to demolish the pub and instead have invested heavily in making it a success.
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.