So quick update, had a gander behind the stat (again) and the fused spur.
S***t show of cabling but I've got a good handle on what's where now.
Stat - has 3c & e from fused spur, where behind the wall socket it picks up the t3 and t4 connections on boiler side.
Fused Spur - mains in top left, boiler out bottom left and stat 3c&e top right.
Plan currently would be
1. disconnect the grey/black from 5c from boiler from the term blocks and the 3c&e to stat completely from the spur, therefore enabling me to remove stat with no live down in the junction.
2. Trim grey/black back to white cover boiler side and also in the spur wall cavity as cables now redundant.
3. New 5c flex from boiler L,N,E & t3,t4 out to Hive receiver.
This would enable fused spur to kill boiler and hive if ever sliced/cut by accident.
Thoughts on that approach?
@CBW @ianmcd