Thanks for the reminder, Bob.  The reference is Bagpipe Family: 7. The Bagpipe in Other Countries.

"Some of the Italian peasantry possess the bagpipe.  It is (or was not long since) common in Sicily and it lingers in the mountainous region of Abruzzi (to the north-east of Rome) where it is often accompanied by one or more separate droneless pipes... The type of music played by these pifferari (i.e. players on the piffero and bagpipers is preserved in Handel's Pastoral Symphony in his Messiah, he having, it is supposed, heard them in 1709 in Rome; for nearly two centuries after that they were to be heard in the streets there every Christmas time.  They were also right into the twentieth century to be found wandering about England and Scotland, wearing sheepskins and high conical hats."