Looks like it could be Olearia furfuracea, Astrid, and it's certainly the right habitat. I remember Malcolm Rutherford putting up images of distinctive-looking specimens of O. furfuracea from up near Gisborne (different from what I normally see of that species), which were reminiscent of these (which I think Mike Thorsen had something to say about). Undoubtedly, other people will be able to comment on that.