As above, ask for proof of an offence.
Some (perhaps) local knowledge may help too. Living in N. Wales there's a few types of van I see quite often. If it was the standard scamera van, with bright yellow markings on the back and two places for a camera on the back - opening hatches, you should be safe. Unless like has been said, the operator took your details.
If it was a more plain white van, and had the blue 'crime prevention' sign, it's the ANPR van. Whilst they don't always record speed, they do look for excessive speed & will photograph front & back. You should be lucky with that if you were just above 60mph in a 60 zone.
Being in N. Wales, you learn quickly what the types of vehicles are & what they do. Usually the hardway
