Another seemingly innocent person...
... With his name, address, fingerprints, DNA, and any other personal information they care to want stored on some database for HM Gov to lose.
There's nothing in this world which would make me "Help police with their inquiries" other than a guarantee that, unless other evidence is found making me a suspect of the case, I would remain uncautioned and free at all times, and no personal information, excluding a proven name and contact details for verification of testimony, was collected.
Any other situation, and i'd feel under pressure to say something just to be released. That's duress, isn't it?