Some years ago I flew to Exeter in a C130 and was parked on the disused runway. Even longer ago I had flown with Exeter Flying Club when I first had my PPL and for old times sake wandered over to their clubhouse to say hello. My old CFI, who was pretty aged when I had flown there, was still the CFI and he asked if he could see my aircraft to which I happily agreed. We wandered back over along with another club instructor and I had just started the tour when an airport security vehicle arrived and said ‘they aren’t allowed here!’ I replied that it was my aircraft and I had invited them so it was all right but security insisted that I wasn’t allowed to invite them.
The old CFI then told security to ‘stop being a silly jobsworth’ and promptly was arrested, along with the other FI for good measure. At which point I decided we were task complete and should really be getting back to EGDL.
As an aside although Exeter Flying Club folded some years ago the CFI was only grounded by the CAA at around the age of 90 having worked for another club at the airport.