“ The two stage test for determining whether the works carried out constituted an enlargement, extension or annexe to an existing building is well established. It requires an examination and comparison of the building as it was …before the works were carried out and the building or buildings as they will be after the works are completed and the question then to be asked is whether the completed works amount to the enlargement of or the construction of and extension or annexe to the original building (see Customs and Excise Comrs v Marchday Holdings Ltd[1997] STC 272 . I must however add a few words regarding how the question is to be approached…First the question is to be asked as at the date of supply. It is necessary to examine the pre-existing building or buildings in the course of construction when the supply is made. What is in the course of construction at the date of the supply is in any ordinary case (save for the example where a dramatic change is later made in the plans) what is subsequently constructed. Secondly the answer must be given after an objective examination of the physical characters of the building or buildings at the two points in time, having regard (inter alia) to similarities and differences in appearance, the layout, the uses of which they are capable of being put and the functions which they are physically capable of performing. The terms of planning permissions, the motives behind undertaking the works and the intended or subsequent actual uses are irrelevant, save possibly to illuminate the potential for use inherent in the building or buildings.”