Tim you mention that you have not heard any other English pipes apart from Northumbrian pipes. It interested me to do a Yahoo search on bagpipes and I found

http://www.gmm.co.uk/ai

One of the charcters Geoffrey Chaucer, writing in the 14thC mentions in The Prologue to the Canterbury Tales, is the Miller 'Ful byg he was of brawn and eek of bones' who 'A baggepipe wel koude he blow and sowne'

On the above site they have a sound recording of the sort of pipe the Miller may have played along with a stack of other sound recording of obscure bagpipes.

Aint the web wonderful!

Ian