"Emily was really great and she was very conscientious of her arm," says Ball. "She had a thing where she liked to tie it behind her back in a way, to sort of ball it up in a fist and fold it behind her back, because for her that just helped her feel a little bit different and feel a little bit crippled."
Browning wore a blue screen sleeve, with the idea being that visual effects artists (from Base FX in China) could then isolate her arm and remove it. They also re-built parts of the frame that the bluescreen sleeve was covering, and added a stump to Laura's shoulder.
The separate arm being carried out was a prosthetic creation that had just enough flex in it to make it feel believable. When Laura manages to find someone to stitch it back on - almost as if it's just a typical clothing repair job - the practical and digital effects work met yet again.