If that was, indeed, the instruction in the regulations at the time, it does make one wonder about the competence of the authors.Yes, that was the era to which I was referring. I've seen some lunacy of bonding from that era in bathrooms (and sometimes kitchens) - even with things like loo roll holders, (non-electrical) mirror frames and coat hooks being bonded!
Perhaps ignoring Table 52.3 is not such a crime - and thinking about everything else is advisable.