The website photos of ships around a courtyard are in the Central Square which is mapped correctly. The other courtyards would require a request to the office owners to access private parts of the office building. They definitely are roof gardens above ground level though so beyond my level of mapping as they would require building parts and 3d representations. The most basic (and most common) building mapping is of the ground level footprint, and the current representation in OSM is correct in that manner. I am local, but not willing to put this level of effort into this building when there are tens of thousands of buildings in Ealing currently entirely unmapped.
Maybe this note could be amended to request that someone creates a 3d representation, because I can confirm here that the closed way is a good representation of the ground level footprint.