Warmtoast, your tale reminds me of the experience I had 30 years ago when returning to the UK through Dover....
I'd been over for a few days visiting Her Loveliness at her flat in Frankfurt and had driven there in my less-than-a-year-from-new Opel Manta. I'd taken the 18:00 Oostende ferry back, which had taken ages as this was before the days of the excellent SeaCat. Over 4 hours, in fact, due to adverse weather. Finally we got to Dover and off the boat to the customs check.
Whereupon some nasty little $hit took a great interest in my car. He ordered me, rather than asking politely, to open the boot. Nothing there except a small suitcase and a carton of bottles - my precise duty free allowance. "Get those that the NAAFI, did you?", he queried (although there was nothing to indicate that I was a member of the Armed Forces).....
"No - at some supermarket in Frankfurt. I think it was Kaufhof"
"Where did you get the car?"
"Ipswich"
"Not through the BFG?"
"No. Ipswich, Suffolk, England - perhaps you've heard of it? And if you want to know, yes, I am an officer in the RAF and I'm stationed at RAF Brize Norton in British West Oxfordshire. Now - is there anything else with which I can help you?"
"Err, no. On your way"
"On your way....SIR??!!"
Obviously the odious little creep had thought he'd been a smart alec and had spotted someone trying to bring a BFG car back without paying tax. Fortunately we don't have to experience the nastiness of such petty officials these days, thanks to the EU!
It would have been a long drive back to Brize that night (no M25!), so I'd taken the precaution of booking into an hotel in Dover. And one of the bottles of duty-free wine certainly helped me to simmer down after the treatment I'd had from that little so-and-so!