The shape yields other quirks. At the top, you walk out onto a granite-floored open viewing gallery. This runs around the top floor. Because the building looks north to the City, obviously the very front of this gallery is the place to be. Except this desirable spot is missing. The structural forehead of that Ziggy Stardust front facade gets in the way. You cannot walk all round. Still, you get great views on three sides, and you can always stare out north through the glass as you toil up the ramp inside.

In the end, these architectural theatrics are a lot of striving after nothing. True, City Hall will make the Mayor and the Assembly look terribly important on camera. Then again, where is the real power base in London, and what is its architecture? It is called Downing Street, and is so restrained as to be all but invisible. It doesn’t have to try very hard at all.

Rock iconography footnote: some readers have pointed out that technically the building does not wear Ziggy Stardust make-up, but Aladdin Sane make-up. I confess I was using “Ziggy Stardust”, hence Bowie, as shorthand for British glam-rock of the early 1970s. To be honest, the picture in my mind was Roy Wood of the band called Wizzard, but I felt few readers would get that reference. Here are Bowie and Wood in their relevant incarnations.