It looks as though I may have come up with a solution! It is not perfect, but it does the job quite effectively. It appears that these dedicated excerpts appear in their entirety. Setting the character count to a preset figure has no effect. This means that I will have to write an excerpt like this for each book that we publish. That is not a problem. It will make the final appearance much better.
This is an example of an 'excerpt'. It has been written in the excerpt section that appears as soon as the POST is selected and opened. I want to make sure that it is at least 270 characters long. What I'm hoping I'll see is this block of text appearing in the box beneath a picture on the PAGE that lists all available audio books. That's just the start. One more line here should just about do it.
In this test, I am writing a dedicated excerpt for the Pride and Prejudice Audio Book blog post. In order to try to align the boxes on the blog archive page I am going to try to write excerpts that are the same length. How long that length should be I have yet to determine. Let's see what three lines of text (as appears in this excerpt box) looks like on the blog archive page.