I beleive trv's are a requirement on at least the bedroom radiators, to satisfy building regs.
CONTROLS FOR EXISTING DWELLINGS
Part L 1, England and Wales.
When a new installation is fitted, the controls should
be as for a new dwelling.
When replacing the boiler and/or the hot water
vessel, the opportunity to improve the controls should
be considered. To be confident that the requirements
of the Regulations are met this would entail the
following:.
a) if a room thermostat is already fitted fit TRV’s on at
least all radiators in the sleeping areas and check if a
new room thermostat or programmable room
thermostat should be fitted.
b) if there is no room thermostat, install either a room
thermostat or programmable room thermostat and fit
TRV’s on at least all radiators in the sleeping areas.
So BG seem not to be complying with Part L
And now remember who told customer that trv's were not required, and the s** took the work off me. BG.