well I missed all the drama on my post but it was all interesting to read just now ....
From what you say would it be true to say ( and I hope this is not an over simplification ) that if someone were to try to claim too much of the house expenses as business expenses following the logic that the "space" is "all business" ( eg maybe if they had a separate heating boiler for the "office" section of the house) ... that it might come back to bite them with regard to the CGT implications ... but that other than that the revenue probably have bigger fish to fry.