My post is my personal opinion. I do not do EICR's so it doesn't affect anyone really. Just shocked to think that anyone would even consider giving a CU a C2 just because it's plastic.
But, present company accepted, that's just the point. For someone who does EICR's, it should not be opinionated.
A plastic CU, in a domestic property, under the stairs should either be a C2 or a C3, or whatever stupid code, or not at all. It quite a specific set of circumstances, and doesn't vary from one property to another. Seems that various property owners, across the country would get different assessments for the exact same scenario.
I don't do EICR's either, kinda glad I don't.