Strange that when I changed the theme just now and posted this with only the photo, it (the photo) doesn’t show up except in the single post.
Let’s see whether adding text kicks it into showing the photo.
No, still not.
OK – changed the theme again. All OK now.
Aha, I think it is a problem with WordPress not syncing or clearing the cache or something, and probably not a theme problem at all. I say that because when I look in another browser, the text ends with ‘No, still not.’ and doesn’t pick up the next short paragraph. Will it pick up this paragraph now?