By amendment I mean whatever upgrades are required to meet the maximum demand of the property after diversity has been applied. Some legacy cut outs and cables don’t facilitate 80A so we may need to do a cable overlay or cut out change or de-looping of the property once we have assessed the size of the loop and whether there are any low carbon technologies already on it. 

Looped supplies, the last I heard, said that you could have 1 LCT in a loop of 4, 2 in a loop of 3 and for some reason 1 in a loop of 2. Anything bigger than 4 and we would de-loop or any more than 1 in the scenarios mentioned we would also de-loop. 

I have since left that post to take up an engineering role in the same business but at the time of leaving, and I’m pretty sure it’s still company policy, but we no longer offer 100A on a single phase supply. The maximum is 80A but 80A can take loads upto 100A for 4 hours within a 24 hour cycle for those who have small spikes for chargers or heat pumps. 

CBSharpe said:

The maximum is 80A but 80A can take loads upto 100A for 4 hours within a 24 hour cycle for those who have small spikes for chargers or heat pumps. 

Just to be clear, that may be the DNO perspective, but it's not necessarily the same perspective in BS 7671, and if the DNO's cutout is used for overcurrent protection of any part of the consumer's equipment (e.g. tails), effectively this could limit the supply maximum demand (or more pertinently for what is becoming a common solution, import limitation, or load curtailment, setting) to 80 A.

Stephen Withnell said:

The DNO did some work a couple of weeks on our single phase, domestic supply, our property is looped off the semi next door.

If the cable comes from the pole to next door and my neighbours have a 100 A fuse, and I have a 100 A fuse, does that mean that the cable from the pole must be rated at 200 A?

I assume not on the grounds of diversity, but with large long loads, the assumption may no longer be valid.