Elizabeth Goudge 
The Little White Horse [EPUB ebook] 

 »For a fleeting instant Maria thought she saw a little white horse with a flowing mane and tail, head raised, poised, halted in mid-flight, as though it had seen her and was glad. » The beautiful valley of Moonacre is shadowed by the memory of the Moon Princess and the mysterious little white horse. When Maria Merryweather comes there on a visit she finds herself involved with an ancient feud. She is determined to restore peace and happiness to the whole of Moonacre Valley. And Maria usually gets her own way…