I really don't know why so many people get their knickers in a knot over this - IT REALLY DOESN'T MATTER!
Some years ago I asked a CAA chap at Kidlington to come over to Brize to do my FI revalidation flight. He turned up in the uniform he wore at Kidlington and was on the point of removing his 4-ring tabs when I asked him not to.
This was because the Flying Club at Brize was, at the time, right next to the Air Cargo hangar and my CAA chum's uniform looked identical to a very senior officer from HM Revenue and Customs - and had the movers panicking that a rummage squad was on the way! Lots of scurrying about moving various boxes ensued; eventually after we'd done my check ride we had a good chuckle at the chaos his presence had caused.