Thanks chaps!
Well, her mum spends a lot of time setting up family 'cheese' pictures, which she's already tired of (as most kids seem to be after a while), so I adopted my usual 'casual' style of shooting to keep her at ease, and get a more natural (and happy) look.
The BOKEH on the water reflections worked out better than I expected - I should have tried the 50mm f1.4 as well, but was just plain knackered after a long day, so was being lazy!
Lighting sucked as it was still mid afternoon, so I kept the sun behind and to one side, and exposed for the face.
Single center AF point positioned over the eyes when possible to get a good sharp focus with f2.8 - AV mode on the camera, letting it choose the shutter speed.
Minor tweaks in PS - other than the obvious B&W and 16:9 crops, which I'm really starting to like the feel of
To Dave's point - photographing other people's kids, even relatives offspring, can be tricky - no magic answers from me, I just try and capture a natural looking kid, and give the parents a picture they want to keep.
As Tim pointed out - after a certain age they become way more self conscious, and I've yet to really take on that age group.
That'll come as this crop grows up I guess!