There isn't much information about this book, probably because it is so old! I bought it based purely on reputation and hearsay so was more than relieved when it arrived and I discovered such a beautiful treasure.
Here is the introduction from the book;

Here is something entirely new in juvenile literature, a strikingly original play book that, while telling a charming fairy story, gives small children a grasp of English grammar that would take years of dull lessons to teach. The story tells of the adventures of Linda and Barry among the quaint little people who lie at the roots of our language. Among the fairy folk there are Sir Pronoun, obliging standing in for busy little Miss Noun; critical Madam Adjective of infinitely changing moods; Master Verb, for ever being hauled over the coals in the Grammar court on the charge of irregularity; small boy Preposition, enlisting Miss Noun's help in the forming of adverbial and adjectival phrases when Lady Adverb and Madam Adjective are too busy or too lazy to appear in person; Wee Baby Conjunction, King Speech's favourite little handmaiden, who holds his hand and guides him smoothly over all the rocky places. The climax comes when Linda and Barry find themselves in the palace of King Speech and his exquisite Queen Poetry and are told by the gracious king of the life of "lifeless" things. THe delicacy and imagination that distinguished Nuri Mass's Australian Wild Flower Fairies makes the Little Grammar People a book for all children who have fairies in their hearts; and teachers will find it invaluable in helping young pupils to understand and respect their own language. Celeste Mass's illustrations, individual and finely drawn, are the book's perfect accompaniment. 1947