Gas fires and regs old and new

Ok, not DIY, but I need to pick the brains of people au fait with the gas regs.
Wife's Grandmother's boiler failed, BG came round, the boiler is now awaiting replacement. While there the BG person decided the Gas fire in the living room was unsafe, said she couldn't use it and capped the pipe or somesuch.
The reasons given (AIUI - it's second-hand info -she lives 200 miles away, and others in the family have been trying to deal with it for her) were that there is a shelf above the fire that is too close, and the fire is set into a fireplace with a wooden surround or panelling too close to the fire. The fire was installed about 25 years ago, and AFAIK works fine.
The situation has been like this now for about 2 weeks or so, the lady in question is 82 years old, and ok it hasn't been that cold yet, but leaving an elderly lady without heating unnecessarily really isn't on. (Note she is the homeowner)
The questions that arise for me here:
1. I've been told, that unless the appliance is a real and imminent risk, such as putting out CO into the room etc. it shouldn't be disconnected without the permission of the owner. (exactly what was said etc. by the fitters etc. isn't clear to me here, but the outcome certainly isn't what she desired).
ISTM that the very most that should have happened is that a notice saying that the appliance was unsafe or whatever it is called should have been given.
2. Presumably the installation was within the regs when it was installed, and knowing the person involved it's likely to have been regularly serviced by a Corgi bod (most likely BG). Even if the installation is in breach of current regs is that grounds for condemning an installation that was compliant when originally installed? Can she be forced to make changes or should this be just an advisory thing in this situation?
Comments from those 'in the know' please (I don't need comments about the crapness of BG, that goes a said - hard info on the legal/ regulatory situation is what I'm looking for)
Chris French, Leeds

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