
Have just looked at the International breed club site - they look lovely :) I don't think they are mongrels - from what I've read there and elsewhere they have longhaired whippet blood in them, a genetic fluke kind of thing, the same way longhaired weims started out (as well as a longhaired dobe I have a pic of and some lnghaired dalmatians!).
I'd love one myself, but apparently they don't like being wrestled with much by other dogs - I think my two would nark it off :p