Thanks all, had a great day photographing 'living statues' with fill flash. Alrhough it felt a little bit confusing at times I'm pretty happy with some of the results Here's a sample:
Well I think in your original post you said you wanted a straight forward technique to give a natural light.
I couldn't tell you've used fill in flash in that picture !
Sporgon, thanks! Exactly the type of result I was looking for; flash without it being obvious. I even wrote your simple guidelines on a sticky note as a reminder. I ended up shooting most of my pictures in Tv because light conditions were varying too much (clouds, sunshine) to shoot fully manual. I did use the camera in fast flash sync as well. I'm really happy and think I've reached a milestone today (but still have much to learn).
5Dmk3, 5Dmk2, Sony NEX-6 | SY14mm f/2.8, Ʃ20mm f/1.8, 35mm f/2, Ʃ35mm f/1.4A, 50mm f/1.8 I, Ʃ50mm f/1.4 EX, 100mm f/2.8L Macro, 17-40L, 24-105L, 70-200 f/2.8L IS II, 1.4x II, 70-300L, 100-400L | E-mount: 16-50 OSS, Ʃ30mm f/2.8 EX DN, 55-210 OSS | 2x FT-QL, AE-1 Program, some FD(n) & FL primes