It has taken me six hours to remove my first attempt, twist new threads and restitch the two fore wings, but I think it was worth it. I am much happier with them now.
I have learnt that diagonal holding stitch does exactly what it was intended to do and is not easy to unpick; not to crowd the stitches but rather give each one some breathing space; that tiny couching stitches are not always the best, for this technique longer ones sink into the foundation stitches where short ones sit fairly obviously on the surface.
For once I have been able to spend an entire day stitching, so it is a little disappointing to only have the same amount completed as I had at the start of the day. I am almost entirely consoled by knowing that this is far better than it was this morning. Had I left it, I think I would have always been dissatisfied with it.