I decided in the end that the Bole/polyjuice bit was just too much exposition for this piece, but it involved Bole being an agent who dispatched of Muggle borns and Percival interfering with that job.
I am so glad you enjoyed the piece and that you got to that sort of tight, wound up space when you read it- I couldn't ask for a more successful indicator. Cheers and thanks for the comment!