Written before 1990.  It is a standard length children's story (circa 100 pages or more) about a group of children.  The first part of the story they have a playful time in a castle and a
moat etc...  It is described in such a lovely way.  The second part of the story (maybe they go back after they have grown
up?) they go back and it is described in a more realistic 'tarnished' way.  The moat is dirtied up and the grass has all died etc and it's not quite a castle etc etc etc....