Thank you all
The last 6 months has been a learning process on the type of images wanted by publishers etc, and most of it has come as a surprise. Images I thought were of no real use, have been the most popular. Macro stuff that I have done for my own enjoyment, has turned out to be my best asset. The image printed in Aula is of a simple droplet of rain on the tip of a blade of grass. But when added to the theme of the section of the book, it tells a story. It speaks of "the price of water, how people don't value it, and how they could consume much less".
Funnily enough, the "Outdoor Living" article is called "water wise" and is using the same image, plus one other from that series. So I'm thinking that both publishers have thought the same thing when viewing that image (I've attached it to this post).
I've now been approached by another 8 publishers over different images I have, so this may be a good starting point for me. All have been regarding Macro shots of things from phone key pads to PC parts, so this seems to be the way to go.