Malcolm Saville provides a good reason for writing

From chapter 6 of Rye Royal (1969):

But when they reached the castle they saw that it was now surrounded by a high wire fence bearing a notice "Entrance to the Public prohibited" and Dickie said he would like to write a protest article about this sort of thing happening. 

"Anyway," he added. "Things and places are hardly ever what they were. I suppose that's another important thing about being a writer. You can help people to remember.

There is more about my favourite writer as a child on the Malcolm Saville Society website. The castle mentioned here is Camber Castle.