Have used multiple large boards in industrial settings but never seen 52 way in domestic, even in industrial it is common to use multiple smaller boards at level 3 each located closer to the final loads.
I would question his qualifications.
That 52 way is a domestic three phase supply in France, thirteen row is the standard, in Germany its twelve row, but would still be 48 way, off that 52 way board are two additional smaller boards to supply the Kitchen and Workshop off the Kitchen board is another board in the pump house box at the swimming pool.
Horizontal supply to be at the top and then down to sockets and keep all runs visible. Be prepared to increase the number of sockets & outlets as work and tools require
The requirements for the test and inspection of a ring main have to confirm that it is infact an intact ring, ie each conductor leaves the board and returns which is a simple test and is done by placing each conductor in series with the other conductors so start with Live and Live return connect to Neutral, the neutral return you connect to the CPC and CPC return is the other end of the loop, now if there is no continuity then one of those conductors is open.
The ones we used were for Dc current measurement, the PR30 and also some larger ones for just Ac and they were like hoover is to a vacuum when it came to current measurement but now they are nolonger grey but Fluke yellow with a price hike to match .
For electricians it was a routine test, you just did it with a continuity tester and a good low ohm meter, preferably a four wire job which I still have somewhere.
I may be missing something but I was under the impression that a 2.5mm ringmain will take 32A? By using 4mm surely you aren't gaining anything as you still can only pull 32A through the MCB. Doesn't that just use more copper and cost more to achieve the same thing.
It helps if there is a break (fault) somewhere in the ring. If the ring is complete it does a sort of crude load balancing, but if there's a break it effectively turns into two radials - much of the load could then be on one side of the fault taking power through a single cable only rated for 20A.
No worries, 2.5mm on its own won’t carry 32A, the ring allows the current to flow in both halves, so effectively you achieve 5mm CSA. For a radial you have to use 4mm CSA which again depending on distance is the minimum thickness of wire that’s required. 
There is no loop as such because each conductor L,N & E leaves the board and goes to the first socket with the others just daisy chained and at the final socket there is no return to board unlike the ring. But yes you still have determine the loop impedance of a radial to determine if it is low enough to allow sufficient current to operate the protective device but you no longer measure R1 + R2 as you just plug the tester into a socket and push the test button which gives you the prospective fault current. Yes things seem to change even faster or is it us just slowing down !
Radials in 2.5 need a 20 amp protective device whilst those in 4mm use a 32 amp protective device as you know it is all about protecting the cable and instalation and not what it is connected to, ie the final load. With radials you can have for example six sockets and then split the radial so as you have two more radials running to other strings of sockets which is something you cannot easily do with a ring.
