Four Types,
I can't quite work out if you're being serious or attemtping a wind-up. If you have business on a base, you can gain access according to the current requirements. If you want to go to the mess to socialise as a non-member, you have no right of access. And why should you have?
You can always get a mate to bring you in, but I would be very disappointed if a guard on the gate were to to open the gate to you on the basis of your "Don't you know who I am? I served here for 35 years!" Hardly counts, does it?
You left, you handed in your ID, you have no need nor right to enter the establishment. It's the same for all of us that have left. We are not a part of the Armed Forces and cannot, therefore, expect to be able to walk freely in their secure areas.
I'm surprised anyone would think otherwise.