I've now been able to go inside my current stat and have confirmed that it is indeed a Danfoss RMT230 (with parallel accelerator) and is fitted to a metal back box.
The cable is 3-core-and-earth with old colours : Red, Blue, Yellow and "Bare".
Connections are currently wired as follows :
Red (presumably "Live") → Terminal 1 (COM)
Yellow (presumably "Switched Live") → Terminal 2 (ON)
Blue (presumably "Neutral") → Terminal 4 (N)
Earth → Back Box
I've been looking at the wiring diagrams for the Danfoss TP5000Si (battery powered) and TP5000MSi (mains powered) versions and believe they are wired as follows :
1) Battery Powered
Red → Terminal 2 (COM)
Yellow → Terminal 3 (NO/ON)
Earth → Back Box (as before)
Blue → Unused and 'taped-up'
2) Mains Powered
Red → Heating Terminal 2 (COM)
Yellow → Heating Terminal 3 (NO/ON)
Blue → Electronics Terminal B (N)
Earth → Back Box → Electronics Terminal Earth
+ Short piece of Red wire connecting Heating Terminal 2 (COM) and Electronics Terminal C (L)
My main question is : Are my wiring details above correct ? Have I got them right ?
Also : Any advice re the choice of battery powered or mains powere ?
Many Thanks