The wiring has remained unchanged from the original install by BG also the 230v the 5 core is not coming to the thermostat that is managed by a three core. Also the boiler is on a spur. The first image shows the original wiring with the thermostat still attached.
My old system is comprised of a drayton LP111si Single channel programer and a honeywell wired thermostat. When I removed the old programer to try and slip the hive on it all powered on and turned green but would not physically activate the boiler. I know there are 2 cables used to control this...