I've been to many meetings in MoD with people without clearance - they get an "escorted access" pass and in the meeting we cannot talk above unclassified level.
.... when one was serving in the Ministry about 12 years ago, so was the Duke of York, who was a serving two-and-a-half (or maybe Cdr?). Our work overlapped in some areas.
Bumped into him in the corridors one day, he was with his younger bro Prince Edward, who was wearing a pink (!) Visitors' Pass - must be escorted - rather than the green unescorted variety .......
