His (with its variants is and ys) was much more common in this construction than her or their. The his-genitive, whichever pronoun is used, was most prevalent with proper names and especially after sibilants, as in Mars, Moses, Sands, and Grace, an environment in which the genitive ending is homophonous with the unstressed pronunciation of his. Although the his-genitive in Old English must have been the sort of topic-comment construction cited above, its early Modern English frequency was certainly due, at least in part, to a confusion of inflectional –s and his. The construction has survived, archaically, in printed bookplates: “John Smith His Book.”