UK - once, arriving in EDI (or less likely GLA) about 13 yrs ago. I had a small flat box with a framed picture in it, officer specifically asked about and x-rayed that, I can only assume it might have been the flag which caused the inspection. no interest in large carry-on, luggage, etc., but the officer was waiting for me when I went through the green door. Beyond that, questioning was cursory.