I worked in that pub in the 90's and like most of that pub chain at the time the wiring was fairly rough, and likely then old Crabtree C50 boards, that board shown in the link (not sure its the right board, maybe a press pic, seems too many new colours for a pub even after a refit) seems it was not done by this particular guy,called Db1A so maybe bunched off an older board Db1.
Lots of these newer boards were tagged onto the ends of old pyro sub mains and some of the work we see its no surprise for a poor earth, sometimes its been in years before even noticed.
I went to one pub where the whole accommodation was rewired, so you think somewhere along the line something was tested, it was only when the plumber got a bad shock fitting a shower with the Mcb off, that i got sent there and found the pyro feeding the C50 board had been phase marking wrong leaving the whole install reverse polarity.
Could have been lethal to me too, because the old C50 boards had a lot of Neutral copper exposed with the cover off and like most of us back then, safe isolation was a bit complacent regarding removing covers.