"MoD CS, apart from the odd tosseur who might claim to be a 'Gp Capt equivalent' or whatever, provide pretty good value for money in support of the UK's Armed Forces"
The equivalent rank muppets are out there still - I find them as fun and interesting to deal with as the many retired RAF and other military personnel who continue to use their military rank long after they've left the service and gone into new jobs.
The issue is one that at its heart is very simple - namely that all three branches of the military, and the MOD CS all have ranks and grading systems with different titles. The 'equivalent rank' system simply translates the titles of these ranks/grades into a roughly unified structure so people know roughly how senior the military / CS they are dealing with is.
While some CS do get confused about the equivalency (drawn in part I suspect from working with a rank obsessed military culture), I do find it depressing that some military chose to ignore that many CS are actually very experienced, know what they are talking about and worked bloody hard to get to whatever grade they occupy. It is a little frustrating that some in the military appear to throw basic courtesy out of the window in joint environments, and where personnel perhaps treat a military SO1 with respect bordering on sucking up, while ignoring, or treating with contempt the CS (who could easily be their 1RO) who they see as untermensch.