OK, thanks I get it. As I said in an earlier post I suspected that SPD's were really meant for high voltage transients based upon what I saw in the video I watched. Thanks to you and Bazza for confirming that and that lost neutrals would not be handled by the SPD. Take care.
I have a prediction for you all. I predict that many electrical contractors will come to not actually understand the requirements, and we will start to see complaints from landlords that they've got an Unsatisfactory where there's no risk of serious injury to, or loss of, human life, no risk assessment has been done, the total value of the installation and equipment therein does not justify such protection.... And people being told that they can't have their new cooker circuit unless they have an SPD wot is now mandatory. And so on and so on.