VERIFIED SOLUTION i
|It is possible to create base maps in Spectrum using a TAB file in any projection. In MapInfo you can choose British Grid with 1mm accuracy|
Step 1 - Create tab files in the 1mm accuracy British projection and save them in MiPro.
Step 2 - Upload to Spectrum.
Step 3 - Use in SSA.
In step 2 you can create a tile map for the data and bring it into SSA as base map (please refer to the help file on how to create a tile map).
UPDATED: October 30, 2017