The OP has stated that the fire is 300 mm off the floor. One would expect that would be the bottom of the fire.
Now we dont know what the MI says, but in the absence of further information, one could conclude the burner is going to be at LEAST 100 mm greater than the default regulation requires.
In that case the expectation is that the gas engineer was acting ultra vires in stating the fire was NCS/AR/ID. In any case he turned off the whole gas supply when that was not necessary either.
It appears from the limited evidence that he was acting totally unreasonably! In that case my advice would be for the owner to obtain a clearly worded written report on the situation from another gas engineer and if that supports our expectation that it was turned off unnecessarily then he should claim his costs together with compensation for the inconvenience of having no gas supply for several days. The other engineer should be able to turn the supply back on.
Tony
