It is TT and the supply may be looped through next door, so adding 6kW of load with the kettle and heaters may bump up the neutral voltage significantly, but there wasn’t anyone at home next door so I don’t know if it is looped and I cannot imagine there were any significant loads next door any way.

Four doors up there’s an EV charger, but that’s the only one I could see and I could not see any PV on neighbours houses, this house does not have either.

It is TT and the supply may be looped through next door, so adding 6kW of load with the kettle and heaters may bump up the neutral voltage significantly, but there wasn’t anyone at home next door so I don’t know if it is looped and I cannot imagine there were any significant loads next door any way.

Four doors up there’s an EV charger, but that’s the only one I could see and I could not see any PV on neighbours houses, this house does not have either.