Neutral in the High resistance earthed systems

It is certainly done, and is a half-way house from TNx to the fully floating supply (IT) situation,. There are a couple of advantages in terms of fault currents being reduced, and everyone knowing how much earth leakage there is while in use (from the neutral to CPC voltage) . Earth bonding diverted currents are lower, as  are the chances of an imposed shock voltage on things like outside taps or neighbours plumbing and gas pipes 

But,like IT the insulation, and perhaps test , requirements need to be stricter - in the event of a hard fault to ground on say phase 1, during the time it takes ADS to pick up, the other two phases are at 415V to ground, and the neutral is a 240 to ground, Correctly wired loads don't care, its a situation similar to the wild leg 3 phase in the US, the voltages between the wires remain  correct.
But, those of us used to assuming that neutral is at or near earth potential, and that includes designer  of CUs with unshrouded  neutral rails, might be set up for a failure.

The resistor itself needs to be extremely robust, as it only ever get shock loads, and must work at least as reliably as the RCDs, ideally more so.

But yes, its very much a thing  in parts of the world where the ground is a poor conductor, or nearer to home,  like the London Underground DC traction, where the power is maintained against a first fault, to allow trains to be limped out of tunnels.  I have been told In the old days the traction supplies  were earthed at the centre tap of two lamps, and an earth fault on one line meant that sides status light went out, and the other lit up  extra bright, but power could be kept on if required, and the fault current was only that of the filament lamp, and unlikely to start a fire.
Mike

As Mike says, but to add that BS 7671 does "strongly recommend" that the N is not distributed in IT systems (NOTE to 411.6.1) ... although not prohibited,

   - Andy.

As Mike says, but to add that BS 7671 does "strongly recommend" that the N is not distributed in IT systems (NOTE to 411.6.1) ... although not prohibited,

   - Andy.