I went to London 2.5 years ago, I remember this housing structure. Know what it reminds me off? Jurassic Park: San Diego as seen in The Lost World: Jurassic Park. Concrete, arena type thing in the middle, good room for gawking. Replace the camels with some triceratops and suddenly the place becomes twenty times cooler. :-D
The exterior of the Casson does have the appearance of a backdoor loading bay in a shopping precinct. I think the only way round this is with planting. However, I am not aware if English Heritage would even permit this as it would effectively screen some of the structure off from public view.