...But I should have stuck to my instincts - and jimbo takes the prize for mentioning her name first (CONGRATS, JIMBO!! ) because according to this blog, the "stunt woman" is indeed Bella Heathcote.
Sorry, I think I should say that the woman isn't confirmed as Bella Heathcote. When I was talking on email with the photographers about using the images for my site, they asked me if I could identify the actress – my response was to say that I couldn't be certain, but if it was a known member of the cast, I thought it might be Bella – which is where they got the info. I think it's quite likely it is her, but obviously something-I-think-from-glancing-at-a-photo isn't proper confirmation by any stretch.