“i) The first is that the works constitute a residential conversion to the extent only that they consist in the conversion of a non-residential (part of a) building. If and to the extent that the works consist in the conversion of what is not non-residential, then those works are outside the scope of the subsection. ii) Secondly the conversion qualifies not only when converting the whole of a non-residential building but also when converting a non-residential part of the building. If part is non-residential the other part must be treated as Residential, ie, not non-residential. iii) Thirdly the conversion qualifies if it has any one of three results set out in (a), (b) or (c), namely (a), a building designed as a dwelling or a number of dwellings, or (b), a building intended for use solely for a residential purpose or (c), anything which would fall within paragraph (a) or (b) above if different parts of a building were treated as separate buildings. iv) Fourthly, s 35(1D)(a) needs more analysis. It covers two types of conversion. The first is the conversion of a non-residential building. It is easy enough to see when a non-residential building is converted into a building designed as a dwelling or number of dwellings. There is an old building and after conversion a new building and the question is simply whether the new building is designed as a dwelling or number of dwellings. The building itself remains the same: it is its use which has been changed. But paragraph (a) also applies to the extent that a non-residential part of the building is converted. The question then arises, "Into what is that part to be converted?" The clear answer given by the language of the subsection is that just as in the case of the conversion of the building itself, the part of the building likewise has to be converted into a building designed as a dwelling or number of dwellings. Paragraph (a) does not require the part of the building to be converted into a part of the building designed as a dwelling. The subsection does not say that. Words would have to be written in to give it that meaning. It seems to me therefore that on the proper construction of paragraph (a) it is enough if the non-residential part is converted into, that is to say changed in its character and made part of, the new building which results from the conversion and it is in the building as a whole that one must look to find whether it - the building as a whole - has been designed as a dwelling or number of dwellings”