Third edition CoP (published 2018, aligned with 18th edition) says:Is that still true today, post 18th edition, and if so does this in fact render PodPoint's attempts to invent a magical open neutral fault detector totally irrelevant, if the IET CoP mandates an earth rod anyway?
For single-phase installations, a voltage-operated device that will meet 722.411.4.1(iii), when and if available, may be an appropriate solution. (At the time of writing these devices are not available).
So it all comes down to whether PodPoint's device actually satisfies 722.411.4.1(iii).
As previously discussed, in my opinion it is not possible to do so without having an earth electrode - though a device based on monitoring the supply voltage only might provide a sufficiently large proportion of the safety benefit to make it a good idea, it doesn't meet the requirements specified in the regulation.