Officially unarmed. But plenty of the posts were rural, and although the advice received was that if Farmer Giles turned up at the hatch with a shotgun you were to let him have the post, a fair few of us had FACs and shotgun licences. On my first post we made a conscious decision not to use the siren nor maroons as the only people who would hear them were one farmer and his sheep.The thing to remember was that although they looked military(ish) ROC Posts like this were officially completely unarmed and staffed by RAF Civilians. Great store was set on their Non-Combatant Status, officially at least
Our legal status was a weird one. I was a uniformed part time civil servant, technically under Home Office control. Yet we were also classed as TA & VR, possibly at the same time (I think that I last checked that about 35 years ago, so I may have timings wrong). Yet we had officers, but they weren't commissioned but warranted, and full time officers still had to do the vicars and tarts course at Cranwell even though they were civil servants.
Back to the subject of the thread, at stand down in 1991 there were I think 872 active posts nationwide. However at one point there had been about 1,500. Most of the remainder had been closed, and presumably abandoned, in the 1960s. There was actually a post in my home village that closed in 1968. In that pre internet age most of these would quickly be forgotten, so I would think that some would be ideal for illicit arms storage. And who could resist the irony of an illegal arms store being provided by the British government?