The Illustration for the front cover of the book (Gouche and polychromo pencils on watercolour paper).
The eureka moment was at 2am, as I read the book. I suddenly wondered what shape a corrugated cardboard box would make if opened out. This item was the first piece of comfort the protagonists experienced in days following the initial storm and flood. As it happened - it didn't make a cross but with a little judicial tearing I was able to achieve an impression of it - subtly. Maeve's an Irish nun and she says the book has a strong spiritual element. I managed to hint at this but without putting too much weight on it.