Hi @IanFerguson
I am assuming you have a gas boiler with radiators for your heating rather than something like a heat pump or under floor heating.
You are correct in that you shouldn't have a Thermostatic Radiator Valve in the same room as your Thermostat.
I suggest asking your local authority to highlight in the building regs where it says your thermostat has to be in the hall, not the local authorities interpretation of the regs in any document they provide. Here is a link. You can search for thermostat in the regs. I've never seen the restriction they mention but I am not a qualified person.
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1133079/Approved_Document_L__Conservation_of_fuel_and_power__Volume_1_Dwellings__2021_edition_incorporating_2023_amendments.pdf
If you took the TRV out of you living room and put the TRV the hall, then put the thermostat in the living room then you shouldn't have the issue of a TRV and Thermostat in the same room. This may be what is causing the issue with the local authority.
It also doesn't make any sense to me as there are portable thermostats depending on the control system for your gas boiler.
It also sounds like it is worth checking to see if your radiators are balanced if you are getting uneven heating.
Do you have a link to your local authorities website containing the limitation they have told you that you could share with us?
I’m curious, is this the local authority building control telling you directly or a company working on your gas central heating?
