Today's fun. I was only there to change a cracked socket front a quick end of day job, which I did.
As far as I can tell it's TT (found the rod and getting 2 ohms Zs from CPC bar) but can't verify what else is bonded at this point. There's only one earth wire that isn't a CPC coming into the board, so suspect there's a MET somewhere in Narnia.
I didn't want to try a high current test in case there's an upfront RCD in there too!
Also of note is the split load board, so potentially inadequate fault protection for right hand half if parallel paths are removed.
I had to say that I couldn't prove I'd left it in a safe condition and I'd have to return, take the panel off and see what is actually going on.
(The panel is actually about 4 times as tall as shown and extends to the top of the stair well just to help matters)
Some photo's pointing my phone in the hole...
The earth wire below goes to an old oil pipe not the cut-out btw