If I add a caption to an illustration, say, the caption text consists of
Category Number, and text from the "caption" box in the dialogue.

There is white space automatically added between the category and the number,
but not between the number and the text.  So, for example, you get "Illustration
1Fred"

You can, of course, work round this by putting your own white space in the
dialogue, but it seems a bit clumsy.  Surely the white space should form part of
the number?