There is indeed a screw which secures the rearmost edge of the bumper to the front wing, but unfortunately the bumper plastic area that the screw holds has broken away from the rest of the bumper. There are other clips which hold it so I was able to snap it back into position. It remains to be seen if it will stay there. I don't know if it's feasible to glue the bumper back together. There was a dent in the bottom edge of the bumper so I'm guessing my partner nudged something. This is why they don't get to drive my car!
The wheel arch liner was also ripped in two. I drilled some holes and 'stitched' the edges together with cable ties to stop the bottom edge of the bumper flapping about.