Keppel-Jones's study focuses on a period of 275 years, during which iambic pentameter variations were conducted with special precision. Representative blocks of verse are chosen from major poets in original authoritative editions, and each variation is analysed on the basis of all cases of that variation. To give precision to certain of the principles, Keppel-Jones follows the linguist Bruce Hayes' definitions of boundaries between word-groups, but handles this material in such a way as to be understood by the general reader. Keppel-Jones found that the practical result of this study is a new metre that he allows him to apply the principles of iambic variation to the anapest. His fascinating and original approach to iambic pentameter will appeal to scholars in the field and also to people with a general interest in poetry.