Highways Agency Traffic Officers have the power to stop these days independently of police:
“Highways Agency Traffic Officers have powers to stop vehicles on most motorways and some ‘A’ class roads, in England only. If HA traffic officers in uniform want to stop your vehicle on safety grounds (e.g. an insecure load) they will, where possible, attract your attention by
flashing amber lights, usually from behind
directing you to pull over to the side by pointing and/or using the left indicator.
You MUST then pull over and stop as soon as it is safe to do so. Then switch off your engine. It is an offence not to comply with their directions (see ‘Signals by authorised persons’).
Law RTA1988, sects 35 &163 as amended by TMA 2004, sect 6
I doubt their powers extend any further than that. Even the police have no powers to direct you to answer research guff. But what’s the betting that your vehicle would suddenly be deemed unroadworthy in some respect should you be a bit of an arse about it?