It turns out that the Reynolds 501 frame of the Dave Quinn mountain bike, kindly karma'd to me by @KondratievsBike (separate thread here: https://www.retrobike.co.uk/threads/a-tale-of-two-dave-quinns.465155/) was made for Dave by Orbit Cycles, one of the frame builders he worked with.
Dave kindly confirmed this in the course of me trying to track down the builder of the 531-framed bike in the other thread.
This one is most likely a 1989 bike as kitted out with Exage Mountain.
Made by Orbit means it's a very close relative (brother? cousin?) of the Orbit Frontier. More photos to come on the other thread as I clean it up and recommission it.
Dave kindly confirmed this in the course of me trying to track down the builder of the 531-framed bike in the other thread.
This one is most likely a 1989 bike as kitted out with Exage Mountain.
Made by Orbit means it's a very close relative (brother? cousin?) of the Orbit Frontier. More photos to come on the other thread as I clean it up and recommission it.