Good in flight pose Ian, although I would perhaps wish for the wings to be slightly lower near the bottom of the downstroke. It seems as though you have kept the whites in check even though the light looks quite harsh. I would particularly like to see a looser crop with more space for the bird to fly into on the left.
What a lovely image, Ian! I love the contrast of the whites with that super dark green BG. I'd fix the two ruffled feathers in the front wing as they immediately grabbed my attention. I'd also play with the head/neck area to take out some of the extra gray and bring the feathers closer to the whites of the wing - but not all the way as bright as they are supposed to be in shadow to some degree.
I downloaded your image and threw a ROT's grid on it (Ctrl + ") and the eye/head is right at the third mark so I'm not sure I'd add too much extra room. You might take a look at adding a very small slice behind the feet and about that much to the left as well just to keep your proportions even.