My hope was that the pupils would use the feedback to see where they had "gone right" as well as where they had gone wrong, and would be able to use it to help with corrections.
As it turned out, these feedback forms (returned to them electronically via the maths department Moodle installation) were time consuming to complete, and hard for pupils to interpret. Some of the youngsters in my Higher class found them very useful, but most didn't, and the forms didn't have any impact on the quantity or quality of corrections being done.
You win some you lose some! I guess this idea might work for someone else in a different situation.