I got pulled in at a ‘checkpoint’ by a police officer last year. Busy main road heading into town, 11am. Lane 1 of a busy dual carriageway was coned off for about 100metres to facilitate said checkpoint, causing major holdups…
Approached by a lady, hi-viz jacket on, clipboard in hand. Turns out that a ‘traffic survey’ was being carried out, said lady wasn’t a police officer, the police were only there to pull motorists over.
Very miffed at having my journey delayed, I asked her if I was legally required to answer her questions, ‘No’ was her reply. So I wished her a pleasant day & drove off*
*( Immediately driving off wouldn’t have been possible if there had been another car in front of me )