Lur & the Pied Piper of Hamblin
When looking at the instrument used by the Pied Piper of Hamblin, it looks like a lur. And he is dressed like what modern people would see as a clown. The bright colors would be very appealing to children.
From a fiction perspective, my theory is that the Pied Piper of Hamblin coincides with the 1283 Scottish decree to increase wolf hunts and the children are used to feed the vampyre and wolves.
The non-fiction reality is likely another planned targeting of groups considered “pure.” In this case, it was the children of Cathars targeted by the piper.
Are those mutually exclusive? No.