What I said was that the person responsible for ensuring terrain clearance is also responsible for applying appropriate corrections when the station temperature is well below isa.
That means the controller when they are providing radar vectors.
ie if the minimum radar vectoring altitude is say 2000ft and the temperature at the aerodrome is ISA -16 deg C then you can not descend an aircraft you are vectoring to 2000ft because their actual altitude will be below 2000ft.
The Reference is ICAO DOC 8168 Volume 1 -
This chapter deals with altimeter corrections for pressure, temperature and, where appropriate, wind and
terrain effects. The pilot is responsible for these corrections, except when under radar vectoring. In that case, the radar
controller issues clearances such that the prescribed obstacle clearance will exist at all times, taking the cold
temperature correction into account.
(My Emphasis)
The UK does not provide any corrections (see AIP GEN 3.5.5). Thus you as a radar controller have to come up with them when vectoring.
Regards,
DFC