The motion is mostly through camera movement.
The other option for this was to use After Effects CC Force Motion Blur effect as demonstrated by my classmate. However, I want to keep this all within Nuke, so it was important to get the pass to work.
The vector frame
It is a 32-bit (float) vector sequence which you use in Nuke to determine how much the image should blur in each frame by using the colours it provides. Shuffling out the image and setting it to 'forward' and then copying this into the comp in order to provide for the vectorBlur node allows this to work. In this node I set the method to 'forward' to sync this up and the shuffled UV channels to 'motion'.
The vector blur applied
