GQ built and the look of the main flap makes me think of the GQ rig called the "System" that was introduced in the late 70's/early 80's, around the time that the GQ "Unit" main was introduced. The only "System" that I jumped was owned by Tom Manning or Guy Manos (I think). It had a pull-out, and I only jumped it once or twice at Homestead FL between '78-'81.
***I only looked at the rig briefly, but it's a British rig from the early 80's, a Wonderhog-style rig that I understand was built by GQ.