Beocare have solved the radio station issue for me.
Apparently B&O maintain a data base for the Beosound 5 Encore which is manually updated on request.
They ask for the country, name and URL of the staion on Tune In, and then they can add it to the data base…
Once this is done, a complete power off and reboot of the Encore, enables the new stations.
It took a while, but we are there now.