As a former fast jet nav, I agree that advances in avionics have meant that the navigator's role in the future RAF will disappear. What E- appears not to have considered, in the case of the GR4, is that the queue of pilots wanting to fill the back seats of GR4s is likely to be rather short. Since most GR4s are single-stick, the rear seat pilots would, presumably, not be permitted to log their flying as pilot hours. How popular would that be?