"Before anyone gets too worked up; all UK domestic supply is single phase, and won't be using these 3 phase meters."
Nope. I have 3-phase at home.
A previous owner had a swimming pool with a 3 phase heater (and presumably a huge energy bill!).
Needing more than 24kW (100A single phase) is rare in a domestic situation, but not impossible. A friend is also looking at it - adding up electric car charging (7kW), induction hob (8kW), and air-air heat pumps (7kW) he's getting pretty close to the limit. Don't go boiling the kettle at the same time.