Waldo Clarke, D., Munro Mackenzie, M.D. Modern English Practice - Key to the Exercises

Longmans, 1957; 69 pp. (PDF-- 74pp.); black and white, no pictures. Key to D. Waldo Clarke & M.D. Munro Mackenzie: Modern English Practice, which is available here at /file/304754/
The key fully corresponds to the book. The full set, though old, offers plenty of high-quality grammar exercises.