Thats the information which i was after!(the second meter being customer owned, ie will be mine - i will bin it then - i obviously wanted to see what someone in the know thought though in case i binned something billable!), thankyou for the reply.
Yes that is all that is installed at the moment - for the current use that small 40A breaker is more than adequate (it is a large agricultural barn which now has C3 change of use and planning for the works) - it only has 2 circuits as you may be able to see from that tiny CU, feeding loads of sockets and lights. The entire install will be ripped out back to the supplier meter as it isnt relevant once converted - i am just happy that it has a working 100A feed at all so that we can hit the ground running without any cost on that front.
Interesting about your later point about them simply splitting the supply within the building - i would still hope that this would give the ability to meter separately (as you say, ideal as the main house can be on a cheap any time, the EVs and perhaps water heating could be on a smart tariff or similar which suited them overnight.
Knowing it's an agricultural building the RCCB makes more sense, moisture levels getting too high would be safer with an RCCB also the step down of 40a it all adds up.
If you Google looped supply there is a PDF from UK Power Networks that explains what a looped supply is, it shows share supply between two premises but the same applies if you want two supplies for one property.
But if you intend doing large works to the property you would be better off seeing how much it would cost to upgrade the concentric from the joint in the road/power line and have a proper 3 phase head installed. Also for large building works you will need a builders supply installed nearest to the edge of the property (this is common on building sites) and have the barn supply disconnected.
