Been now asked on three forums, this is forth, looking at the white functional earth fly lead, which it seems is used with VD type so they will still trip if the neutral is lost, fair enough in an extension lead, but in the consumer unit, if one loses the neutral with a TN-C-S supply likely you have lost the PEN, so there is no earth either, so what is the point of the cream functional earth unless connected to an independent earth rod which is not bonded to the neutral.
Please remember, I am a retired electrician with some 50 years plus experience, and I don't know the answer, maybe they are only for use to TT and TN-S supplies?