Borderreiver wrote:
What I do not know is whether there is a problem at the NLS/ Historic UK 25 Inch end or a problem at my end with Transdem.
Not a problem on your side. I just ran an https traffic analysis. NLS has moved the data to a different server. The 25 inch maps are now hosted in the Amazon Cloud. I will update the settings and report them here, but that will take a day or two.
If you don't want to wait you can do it yourself: Map Tile Settings | Tile Type Edit | URL part 1 - static.
Note that it has to be updated and verified for every county.
http://geo.nls.ukbecomes
https://mapseries-tilesets.s3.amazonaws.commapdata3/os/25_inch/yorkshire/
becomes
25_inch/yorkshire/