A current topic of interest with the Lauri Lee issue in Stroud.
Lets start with the NPPF definition of Heritage Asset
“A building, monument, site, place, area or landscape identified as having a degree of significance meriting consideration in planning decisions, because of its heritage interest. Heritage asset includes designated heritage assets and assets identified by the local planning authority (including local listing).
Annex 2: Glossary, National Planning Policy Framework, Department for Communities and Local Government, 2012
So yes if the LPA identify it. And this identification include local listing but is not confined to it.
Clearly there are some landscapes identified with literature so strongly they ought to have some form of protection. Take for example the Howgill Fells and their association with the Brontes. The problem is some authors draw a very broad brush, where for example does the landscape of ‘Lorna Doone’ begin and end, or Thomas Hardy’s Wessex, or the Thames Marshes of Great Expectations,or the downs that inspired Watership Down?
A poor guide is whether an author opposed development on a particular site. That is confusing the personal and art. If mentioned in the literature may be, but authors can be subject to the same whims and nimbyism of any neighbour and it can cloud their judgement. Of course if Wordsworth were alive and he had written a poem opposing a particular development that would be another matter entirely. Consider the song ‘men of Harlech’ made famous in Zulu, about a medieval battle lost to history, it represents a verbal history embodies in Victorian times in the song. Yet that song alone makes it impossible to think that the enflade of the castle (yes it is in Wales but the point is the same) could be developed whatever its status as setting of a listed building/ancient monument.