I have been told that Malin Head has a number attached to it, and that the number was visible certainly as of March 2016. I can’t currently get to it myself, and the aerial photographs I used to find these have not updated in the interim. I would like to see it if the sign has been restored.
Update to the Update: See this piece in the Derry Journal
Additionally, since the last time I did some research in to this, the Military Archives has published some of the LOP log books on line. You can find information about them here.
I have approved most outstanding comments by now I think and this project has moved back up my priority list. A look through the comments has suggested there are a few more sites for me to update and as always, any information is welcome.