Al R - I can't agree with you that it is a "Naff" classification. Does that mean the next one up is only slightly less naff? Or the one above that. Or that...
Often things are/were classified simply to deny short term advantage to enemies. Take for example Part One Orders. Or SROs in the RAF. They are Restricted. For good reason. Let's say, the order is "All personnel of X Sqn are to report to the Gym at 0900 for PT". If that fell into the hands of the enemy, say PIRA in those days, it might just suggest to them that 0900 would be a good time to mortar the Gym (for my money, ANY time is good for that, but you get my point, I trust). That same set of SROs is STILL Restricted for at least 30 years. Even though virtually nobody will still be serving 30 years later, let alone be at the same Gym at 0900 with the rest of the sqn.
I guess it's sometimes overkill, but rather that than the alternative.