By the way, would there be any reason she would suddenly lay an egg outside the box (just standing in a garden bed) that could be related to the soft shells??
This particular bird hasn't been on a moult, although some of our other birds have so its possible she may be about to start one soon. thanks for the info about the calcium, I'll give that a try (if she'll let me).
One of our girls has left us soft eggs over the last two weeks, and despite adding a few drops of calcium to their water and giving them food with shell grit, her shells are consistently thin and/or not there (although I suspect not much of the calcium from the water actually went in their...