Thanks
1. First thing I tried was in the Metadata edition. 'English' is allowed, but 'en-GB' was not, and there didn't seem to be any 'sub-languages (?)' allowed
2. The OPF had
Code:
<dc:language>en</dc:language>
and I changed that to
Code:
<dc:language>en-GB</dc:language>
and that seems to work, or at least spell check gave me English (GB) as a language for all files.
It'd be nice if the metadata editor [Language] would allow 'sub-languages' since that's more user friendly that editing the OPF directly (just MHO)