Ian Hay, The Lucky Number — The Side-Step (1923)
“ Had Miss Margot pulled aside the blind at any moment during the next half-hour and looked out upon the moonlit lawn, she might have observed a substantial phantom methodically dancing the fox-trot with itself, counting audibly the while. “Will you stay and take a cup of tea?” inquired Mademoiselle after the next lesson. “I’ve no one else coming this evening, worse luck; and you don't look as if you had too many people to talk to in your spare time, either.” Now that William Peck came to think of it, this was true, though no one had ever said it before. ”
