In message , at 15:49:10 on
Thu, 12 Jul 2018, Tim Watts remarked:

As a digression, I believe the rules have now changed so a consumer
unit must be of metal construction. I assume this too is not
retrospective.

Not quite:

Must be non combustible or contained in a non combustible enclosure.

(Not sure of the exact wording but basically that ^^)

However, that has been implemented as "metal" for the most part.

Thus a really old wooden one is a no-no I suppose?
--
Roland Perry