I'd have to say that all the time these degrees calibrated compasses were in use, post war, (and in the war too) in the Western Desert on 200 mile long range reccy and rescue patrols, operating, direction finding and navigating and training only with compasses, they seemed to be accurate enough then! In my book, that says it all

And in GULF 1, when the GPS satellites were switched off, guess what we used...............