Delafield fans will remember the Provincial Lady asking herself this odd question, and I came across another reference to it yesterday in Winifred Holtby's Women and a Changing Civilisation and was finally inspired to look it up. "Do Shrimps Make Good Mothers?" turns out to be the title of a comic song that was popular in the 1920s. Here are the Two Gilberts (neither, apparently, actually called Gilbert) singing it, from 1924:
As you'll hear, the answer to the question is an emphatic "Yes, they do".