themum
I worked for British Gas for many years, and remember this fire well.
Economic was the name of the firm that made it. They had no connection with any of the other manufacturers that you mention.
They originally manufactured wash boilers, and hand operated washing machines, and were based in Lancashire, Burnley I think it was.
The fire if I remember correctly, had 4 radiants, the outer case was mainly teak, and the operating knob was on top of the case on the right.
It was quite a good fire.
At the time this fire was selling well, most fires of this type were deliberately restricted in efficiency to less than 65%. The reason for this was that any higher efficiency would lead to problems with condensation in the flue. The products of combustion would not be hot enough to rise upwards and go out of the chimney, and a flue lining would have been necessary. That would have severely restricted the sale of gas fires, which neither the gas industry or the manufacturers wanted.
Why have they told you that a flue liner is necessary? Have you got damp patches appearing on your bedroom walls . Are you getting fumes into the room? Sometimes this can happen if you have downdraught into the room. The cause can be lack of ventilation into the room, for instance draught strip round the windows, and a fitted carpet, meaning that if you are sitting in there with a closed door, there is very little fresh air getting into the room. Another cause is often a brick dislodged in the chimney, which is easily put right by a builder, who can access the chimney in the loft.
I would imagine the firm has now gone out of business, but I may be wrong. I will try and find out some more information for you, and if I am successful, will post it here.