Mrs. Dorling’s was an old acquaintance of Mrs. S.

Explanation:
- Acquaintance refers to a person one knows slightly, but who is not a close friend or family member.
- In this context, Mrs. Dorling is described as an "old" acquaintance, indicating that she and Mrs. S have known each other for a significant period of time.
- The term "old" suggests that their acquaintance dates back to some time in the past, further emphasizing the duration of their relationship.
- It is important to note that an acquaintance is different from a friend or a relative. While friends and relatives share a close bond, acquaintances are generally more casual in nature.
- Mrs. Dorling's status as an old acquaintance indicates that she and Mrs. S have likely interacted and known each other for a while, but their relationship may not be as close as that of friends or relatives.
- The specific reasons for their acquaintance are not mentioned in the given information. However, it can be inferred that they have crossed paths and interacted in some capacity, leading to their acquaintance.
- Overall, Mrs. Dorling's status as an old acquaintance of Mrs. S implies that they have a familiarity with each other, but their relationship may not be as intimate or close as that of friends or relatives.