Pretty sure the 24V link also has be disconnected for 230V thermostat operation.
This is what I have been told. You can see that the Hive is now connected to the RT via the 230v connection.
The Hive does exactly what it should be doing, either demanding heating or not, it's just that I expected the boiler's "flame graph" to increase from the almost minimum setting, and probably hence why it heats the home so incredibly slowly.